
Class _SE^ 

Book 



Copyright^ . 



COPYRIGHT DEPOSIT: 



TTbe TRural Science Series 

Edited by L. H. BAILEY 



CITRUS FRUITS 



Eijc Eural Science Series 

The Soil. King. 

The Spraying of Plants. Lodeman. 

Milk and its Products. Wing. Enlarged and Bevised. 

The Fertility of the Land. Boberts. 

The Principles of Fruit-growing. Bailey. 30th 

Edition, Bevised. 
Bush-fruits. Card. 
Fertilizers. Voorhees. 
The Principles of Agriculture. Bailey. 15th Edition, 

Bevised. 
Irrigation and Drainage. King. 
The Farmstead. Boberts. 
Rural Wealth and Welfare. Fairchild. 
The Principles of Vegetable-gardening. Bailey. 
Farm Poultry. Watson. Enlarged and Bevised. 
The Feeding of Animals. Jordan. 
The Farmer's Business Handbook. Boberts. 
The Diseases of Animals. Mayo. 
The Horse. Boberts. 
How to Choose a Farm. Hunt. 
Forage Crops. Voorhees. 

Bacteria in Relation to Country Life. Lipman. 
The Nursery-book. Bailey. 
Plant-breeding. Bailey and Gilbert. Bevised. 
The Forcing-book. Bailey. 
The Pruning-book. Bailey. 

Fruit-growing in Arid Regions. Paddock and Whipple. 
Rural Hygiene. Ogden. 
Dry-farming. Widtsoe. 
Law for the American Farmer. Green. 
Farm Boys and Girls. McKeever. 
The Training and Breaking of Horses. Harper. 
Sheep-farming in North America. Craig. 
Cooperation in Agriculture. Powell. 
The Farm Woodlot. Cheyney and Wentling. 
Household Insects.- Herrick. 
Citrus Fruits. Coit. 



Digitized by the Internet Archive 
in 2011 with funding from 
The Library of Congress 



http://www.archive.org/details/citrusfruitsOOcoit 




THE WASHINGTON NAVEL ORANGE 



CITRUS FRUITS 



AN ACCOUNT OF THE CITRUS FRUIT INDUSTRY 

WITH SPECIAL REFERENCE TO CALIFORNIA 

REQUIREMENTS AND PRACTICES 

AND SIMILAR CONDITIONS 



BY 



J. ELIOT COIT, M.S. A., Ph.D. 

PROFESSOR OF CITRICULTDRE IN THE UNIVERSITY OF CALI- 
FORNIA AND CITRICULTURIST TO THE UNIVERSITY OF 
CALIFORNIA AGRICULTURAL EXPERIMENT STATION 
FORMERLY SUPERINTENDENT IN CHARGE 
CITRUS EXPERIMENT STATION 
RIVERSIDE, CALIFORNIA 



Nefo f|ark 

THE MACMILLAN COMPANY 

1915 

A 11 rights reserved 






- 



Copyright, 1915, 
By THE MACMILLAN COMPANY. 



Set up and electrotyped. Published April, 1915, 



Nortoootl |irfSB 

J. S. Cushing Co. — Berwick & Smith Co. 

Norwood, Mass., U.S.A. 




APR 29 1915 
©CI.A397776 



PREFACE 

The citrusjndustry has now reached a high state of 
development in both California and Florida. Further- 
more, it is progressing with rapid strides. Old World 
practices and precedents have been largely ignored in 
the development of an industry characteristically Amer- 
ican in spirit and new in methods. The readiness with 
which the growers adopt new and better methods is an 
indication of the virility and youthful vigor of this new 
industry. 

The literature has hardly kept pace with the industry 
and is scattered through a large number of periodicals 
and reports. On this account, it is largely unavailable 
to those who need it most. The last comprehensive 
work published in California was that of Lelong in 
1902. This quickly ran out of print and for the last 
six years has been rare. 

The present volume represents an attempt to discuss 
underlying principles in such a way as to emphasize 
the importance of certain stable fundamentals upon 
which the rapidly changing superstructure is built. 
It has also been the aim to describe the industry as 
it exists to-day, and bring together in orderly arrange- 
ment all the information available at this time which 
is worth while. 



vi Preface 

The author has enjoyed the cooperation and assist- 
ance of many friends. The chapter on History and 
Development has been read and criticised by J. M. 
Guinn of Los Angeles. Professors E. J. Wickson, 
E. B. Babcock, B. A. Etcheverry, W. T. Home, 
and H. J. Quayle, together with Messrs. W. S. 
Reed and E. O. Essig, have kindly read and criti- 
cised parts of the manuscript. E. G. Dezell of the 
California Fruit Growers' Exchange read the chap- 
ter on Marketing. I am indebted to my co-worker, 
I. J. Condit, for contributing parts of the chapters on 
insects and fumigation. For cordial cooperation in 
taking the atmometer records reported on in Chapter 
XII, I am under obligation to W. M. Mertz of the 
Citrus Experiment Station. Some historical and other 
data used in Chapter XIV on " Frosts and Orchard 
Heating " has been taken from the excellent graduat- 
ing thesis of Carl Nichols. 

For the use of certain illustrations I am indebted as 
follows: to Carl Nichols for Nos. 10, 14, 15, 64, 65, 
and 86; to W. I. Jones for Nos. 57 and 58; to the 
Roeding & Wood Nursery Company for Nos. 110, 
111, & 119 ; to L. H. Moore for Nos. 113 and 120 ; to 
Professor H. S. Fawcett for No. 128 ; to Professor 
H. J. Quayle for Nos. 139, 141, 142, 143, 144, 145, and 
147 ; and to Professor C. W. Woodvvorth for No. 151. 



J. ELIOT COIT. 



Berkeley, California, 
February 17, 1915. 



CONTENTS 



CHAPTER I 

PAGES 

History and Development 1-24 

First planting of orange seeds in California, 1 — first 
commercial orchard, 2 — other pioneer plantings, 3 — 
early citrus fairs, 5 — the panic of 1884-1886, 6 — the 
cottony cushion scale, organization of cooperative 
marketing, 8 — California citrus shipments, 9 — other 
factors which have made for progress, 10 — history 
of the Washington Navel orange, 13 — the citrus industry 
in Arizona and Sonora, 23 

CHAPTER II 

Geography and Climatology of California . . . 25-39 
Classification of citrus areas, 26 — southern coast, 28 
— interior valley, 30 — northern coast, 31 — the frost 
hazard, 33 — atmospheric humidity, 34 — winds, 36 — 
sunlight, 38 

' CHAPTER III 

Botany, Gross Structure, and Habits of Growth . 40-64 
Classification, 42 — conspectus, 43 — structure of the 
citrus plant, 45 — roots, 45 — wood, 46 — leaves, 49 — 
thorns, 51 — flowers, 52 — pollination and seed forma- 
tion, 55 — polyembryony, 59 — structure and composi- 
tion of the fruit, 60 — seasons of blossoming and harvest, 
63 — longevity, 64 

vii 



viii Contents 



CHAPTER IV 

PAGES 

Varieties .......... 65-83 

Seedling trees no longer planted, 65 — the struggle be- 
tween many varieties, 65 — the survivors few in num- 
ber, 66 — the orange, description of varieties, 66 — 
the lemon, description of varieties, 72 — the pomelo, 
description of varieties, 75 — the mandarin, descrip- 
tion of varieties, 78 — the Swingle- Webber hybrids, 
description of varieties, 79 — the citron, 80 — the shad- 
dock, 81 — the lime, 81 — the kumquat, 83 — the sweet 
lemon, 83 — the trifoliata, 83 

CHAPTER V 

The Citrus Nursery 84-105 

The seed-bed, 84 — source and cost of seed, 86 — 
preparation and planting of seed-bed, 87 — eradication 
of scale from nursery trees, 90 — planting seed-bed stock, 
91 — propagation, 92 — cutting bud-wood, 93 — storing 
bud-wood, 94 — time of budding, 95 — method of bud- 
ding, 95 — training the nursery tree, 100 — balling and 
shipping, 102 

CHAPTER VI 
Horticultural Inspection and Quarantine Service . 106-113 
The California State Commission of Horticulture, 106 
— inspection of interstate shipments, 107 — quarantine 
orders, 109 — State Fruit Growers' Conventions, 109 — 
the County Commissioners of Horticulture, 110 — duties 
of county commissioners, 110 — compulsory fumigation, 
110 — the necessity for inspection, 111 

CHAPTER VII 
Improvement of Citrus Fruits by Breeding . . . 114-131 
Hybridization, 115 — structure of citrus flower, 1 15 — 
cross-pollination, 116 — improvements most needed, 118 



Contents 



— vegetative mutations or bud-sports, 118 — kinds of 
variations, 119 — fluctuations, 119 — mutations, 120 — 
sectorial chimeras or mixed plants, 121 — performance 
records needed, 124 — record of West Highland Grove, 
125 — selection of bud-wood, 128 — pedigreed stock7l30 

CHAPTER VIII 
Judging Citrds Fruits ....... 132-138 

Orange score-card, 133 — orange standards, 133 — 
lemon score-card, 134 — lemon standards, 135 — pomelo 
score-card, 136 — pomelo standards, 136 — packed box 
score-card, 137 — packed box standards, 137 — exhibit 
score-card, 138 

CHAPTER IX 
Selection of Site and Preparation for Planting . 130-146 
Selection of site, 139 — score-card for citrus lands, 139 

— the frost question, 140 — water supply, 141 — soil 
adaptations, 142 — clearing and leveling land, 145 — 
amelioration of hardpan by the use of dynamite, 146 

CHAPTER X 

Planting the Orchard 147-164 

Orchard plans, 147 — number of trees per acre, 149 — 
distance of planting, 149 — contour planting, 151 — time 
of planting, 151 — root-stocks, 151 — digging the holes, 
155 — setting the trees, 156 — intercropping, 159 — the 
cost of planting, 160 

CHAPTER XI 

Cultivation, Fertilization, Cover-crops . . . 165-186 
Plowing, 165 — cultivating, 168 — mulching, 173 — 
orchard tractors, 174 — fertilizing, 175 — humus, 178 — 
green manure crops, 181 — summary of soil manage- 
ment, 184 



Contents 



CHAPTER XII 

Irrigation .......... 

Amount of water needed, 188 — atmometer records, 
189 — sources and cost of water, 192 — methods of dis- 
tribution, 193 — time of application, 195 — methods of 
application, 198 

CHAPTER XIII 

Pruning and Topworking ....... 

Pruning trees in the nursery row, 205 — pruning 
* oranges, 207 — suckers versus fruit wood, 209 — prun- 
ing lemons, 213 — disposition of prunings, '217 — prun- 
ing frosted trees, 217 — reheading young trees, 218 — 
reheading mature trees, 220 — topworking old trees, 223 
— pruning tools, 225 — wounds and dressings, 226 



PAGES 

187-203 



204-229 



CHAPTER XIV 
Frost and Orchard Heating ...... 

Historical cold periods, 230 — season of frost in Cali- 
fornia, 231 — forecasting frosts, 233 — factors influenc- 
ing the occurrence of frost, 234 — local conditions 
affecting frost, 236 — conditions indicating frost in Cali- 
fornia, 237 — how plants are injured by cold, 239 — pre- 
vention of frost injury, 243 — orchard heating with oil, 
252 — requirements of orchard heaters, 253 — types of 
oil heaters, 257 — installation of heaters, 259 — proper- 
ties of fuel oils, 260 — storage for oil, 262 — oil heating 
operations, 264 — care of heaters, 267 — cost of oil heat- 
ing, 268 — separation of frosted from sound fruit, 270 — 
cooperation in frost fighting, 274 



230-276 



CHAPTER XV 

Picking and Packing Oranges 

Importance of careful handling, 277 — causes of decays, 
278 — clippers, 279 — picking bags, 280 — methods of 



277-301 



Contents xi 



picking, 281 — the sweating of green fruit, 285 — the 
acid-sugar ratio, 289 — brushing and washing, 291 — 
grading and sizing, 292 — packing and loading, 295 — 
precooling, 297 — shipping, 298 



CHAPTER XVI 

Picking and Packing Lemons ...... 302-317 

Season of maturity, 303 — market demands, 302 — 
sweating autumn lemons, 305 — storage of winter lemons, 
306 — packing and shipping, 309 — grading and sizing, 
310 — picking pomelos and tangerines, 312 — packing- 
houses, 314 

CHAPTER XVII 
Blemishes of the Fruit and their Prevention . . 318-330 
Insect blemishes, 319 — fungus blemishes, 319 — me- 
chanical blemishes, 321 — bruises, 321 — thorn-stabs, 
321 — cultivator scars, 321 — clipper cuts, 321 — stem 
punctures, 321 — machine injuries, 322 — fumigation 
scars, 322 — shoulder spots, 323 — hail scars, 323 — soil 
scars, 323 — windfalls, 324 — cement dust, 324 — physi- 
ological blemishes, 324 — sunburn, 324 — frost, 325 — 
off-bloom, 325 — mottled-leaf, 325 — exanthema, 325 — 
malformations, 326 — brown spot, 326 — splits and 
cracks, 326 — puffing, 329 — peteca, 329 — dry center of 
lemon, 329 

CHAPTER XVIII 
By-products .... .... 331-343 

United States importations of citrus by-products, 332 

— commercial by-products, 333 — citric acid, 333 — 
lemon and other oils, 334 — unfermented orange juice, 335 

— orange vinegar, 336 — orange wine, 337 — candied 
citron, 337 — oil of neroli, 338 — petit grain oil, 338 — 



xii Contents 



tincture of orange flowers, 338 — essence of orange 
flowers, 338 — dried and candied peel, 339 — lime juice, 
339 — orange paste, 340 — crystallized baby oranges, 340 

— glaced kumquats,341 — domestic recipes, 341 — orange 
or lemon jelly, 341 — orange marmalade, 342 — pomelo 
marmalade, 342 — citrus-rhubarb marmalade, 343 

CHAPTER XIX 

Marketing .......... 344-354 

Methods of selling fruit, 344 — independent growers, 
344 — independent associations, 345 — California Fruit 
Growers' Exchange, 345 — the local association, 346 — 
the district exchange, 347 — the central exchange, 348 — 
collecting and handling money, 350 — exchange adver- 
tising, 351 — method of organizing cooperation associa- 
tions, 351 — Florida Citrus Exchange, 353 — Citrus Pro- 
tective League of California, 353 

CHAPTER XX 
Profit and Loss ......... 355-363 

Average returns, 355 — over-capitalization, 356 — 
eight requirements for success, 357 — capital required, 
358 — cultural costs itemized, 361 — average yields, 362 

— average prices received, 362 — judging orchards and 
lands, 362 — score-card for citrus land, 363 

CHAPTER XXI 
Diseases and their Control ...... 364-402 

Brown rot gum disease, 364 — botrytis gumming, 366 

— scaly-bark, 367 — twig gumming, 367 — leaf gumming, 
368 — gumming of seed-bed stock, 368 — exanthema or 
die-back, 369 — mal-di-gomma or foot-rot, 372 — toad- 
stool root-rot, 373 — mottled-leaf, 374 — wither-tip, 380 



Contents xiii 



— twig blight, 382 — cottony niold, 383 — brown ro't 
fruit decay, 386 — blue mold and green mold, 387 — gray 
mold, 388 — black rot of Navel orange, 388 — brown 
spot, 389 — damping off, 391 — citrus canker, 392_r^- 
melanose and stem end rot, 394 — nail-head rust, 395 — 
scab or verrucosis, 395 — diplodia rot of oranges, 397 

— red blotch of lemon, 398 — yellow spotting of oranges, 
398 — stem end spot, 399 — trunk rot, 399 — galls and 
knots, 401 — black pit of lemons, 401 

CHAPTER XXII 
Citrus Ixsects and their Control ..... 403-430 
Black scale, 405 — red or orange scale, 411 — yellow 
scale, 414 — purple scale, 414 — cottony cushion scale, 
417 — soft brown scale, 418 — citricola scale, 419 — 
hemispherical scale, 420 — greedy scale, 420 — oleander 
scale, 420 — citrus mealy bug, 421 — citrus red spiders, 
423 — silver mite, 424 — orange thrips, 425 — aphis or 
plant louse, 427 — orange tortrix, 428 — Fuller's rose 
beetle, 429 — western twelve-spotted cucumber beetle, 
430 

CHAPTER XXIII 
Insect Control by Fumigation ..... 431-452 

History of fumigation, 431 — fumigation by hydro- 
cyanic acid gas, 435 — tents, 435 — equipment of tents, 
437 — generators, 437 — cyanide, 438 — acid, 439 — oper- 
ation, 440 — season of fumigation, 443 — dosages, 449 — 
dosage schedule for sodium cyanide, 446 — new Wood- 
worth dosage table, 450 — cost of fumigation, 452 

CHAPTER XXIV 

Various Orchard Pests and their Control . . . 453-459 
Citrus nematode, 453 — the pocket gopher, 456 — 
ground squirrels, 468 — poisons, 459 



xiv Contents 



CHAPTER XXV 

PAGES 

Bibliography ......... 460-503 

Other bibliographies, 461 — references to literature 
dealing with particular fruits, 461 — orange growing in 
United States, 461 — growing in other countries, 463 — 
varieties, 464 — breeding, 467 — insects, 467 — diseases, 
468 — lemon, 469 — lime, 471 — mandarin, 471 — 
pomelo, 472 — kumquat, 471 — citron, 473 — references 
to literature dealing with citrus fruits in general, 473 — 
miscellaneous references, 473 — propagation, stocks, 
scions, 478 — breeding, 479 — soils, roots, 481 — irriga- 
tion, 482 — fertilization, 483 — cover-crops and green 
manuring, 484 — varieties, botany, 485 — chemistry, 
judging, 486 — pruning, 487 — curing, storing, sweating, 
packing, 489 — marketing, organization, statistics, tariff, 
490 — by-products, 492 — frost fighting, frost injured 
fruit, 494 — insect pests, 496 — fumigation, 497 — 
diseases, 499 



LIST OF ILLUSTRATIONS 



Washington Navel orange Frontispiece 

FIG. PAGE 

1. Thomas A. Garey, a pioneer citrus nurseryman . . .4 

2. The passing of the old seedling orange groves . . .12 
'?,. Mrs. L. C. Tibbet, who first brought the true Navel orange 

to California . . . . . . . ... 18 

4. One of the two original Washington Navel orange trees 

brought to California . . . . . . .21 

5. California citrus areas ........ 27 

6. Four-year-old Valencia orange grove in Los Angeles County 28 

7. Typical scene in Los Angeles County. Windbreak of Gre- 

villea robusta on right 35 

8. Pinus radiata, a native pine, used as a windbreak . . 30 

9. Orange tree denuded of foliage on windward side by three 

days of desert wind 37 

10. Growth rings in a flattened brace-limb of lemon ... 47 

11. Result of experiment which shows that a girdled orange tree 

may grow new bark. A. Untreated ; B. Treated . 48 

12. Valencia orange blossoms . . . . . . .53 

13. Lemon blossoms showing perfect, partly aborted and aborted 

pistils. Stamens removed in latter case ... 54 

14. Orange flower x 2. p, pistil ; a, stigma ; c, style ; o, ovary ; 

s, stamen ; ft, anther ; e, filament ; d, nectary ; g, sepal ; 

/, petal 57 

15. Polyembryony. Two orange seedlings from one seed . . 00 
10. The earliest known illustration of a Navel orange. From 

Ferrarius' " Hesperides," 1040 07 

17. One type of Australian Navel orange 09 

18. Eureka lemon, uncured . 73 

19. Lisbon lemon, uncured ........ 75 

xv 



XVI 



List of Illustrations 



FIG. 

20. 

21. 

22. 
23. 
24. 
25. 
26. 
27. 
28. 
29. 
30. 
31. 
32. 
33. 
34. 
35. 
30. 
37. 
38. 

39. 

40. 

41. 
42. 

43. 

44. 



45. 
46. 



stakes 



Seedless pomelo, flowers and fruit. From Volckamer's 
" Hesperides,' 1 1708 

Dancy Mandarin orange 

Satsuma Mandarin orange 

Nagami kumquat . 

Citrus seed-bed under lath 

Citrus seed-bed in the open 

Bench-rooted orange seedling 

Orange bud-wood . 

Cutting a bud 

Making incision in stock 

Inserting bud 

Tying inserted bud 

Orange buds in nursery row tied to lath 

Healing of the bud union 

Balling orange trees in the nursery 

A shipment of defoliated balled orange trees 

Two-year-old orange trees, balled, ready for market 

Type of standard Washington Navel orange 

Washington Navel oi'anges showing fluctuations in the navel 
Such variations cannot be preserved by budding . 

Variegated sport. Note white areas in leaves. From Volck 
amer's "Hesperides," 1695 

A variegated sport of Valencia orange. Notice white margin 
of leaves 

Sectorial chimera of Valencia orange .... 

Orange showing sectorial chimera. From Ferrarius' " Hes 
perides," 1646 

What is known as the "Wrinkled" sport of Eureka lemon 
compared with normal fruit. Both from same tree 

Chart showing by dotted line the small proportion of profit- 
able trees, and by heavy line the large proportion of 
trees which only pay for their care. West Highlands 
Orchard. (Adapted from Norton) .... 

Cow peas as an intercrop in young lemon orchard 

Breaking a layer of hardpan by means of a stick of dynamite 
discharged in each tree hole 



76 

78 

80 

82 

85 

89 

90 

93 

96 

97 

98 

99 

101 

103 

104 

108 

112 

117 

119 

121 

122 
124 

126 

127 



129 
153 

156 



List of Illustrations xvii 

FIG. PAGE 

47. Newly set tree properly protected from sun .... 158 

48. Cultivating newly set orange trees with eight-chisel cultivator 16b" 

49. Cloddy condition due to land being worked while too wet . 167 

50. Ground under trees worked with ease by means of orchard 

tractor 169 

51. Orchard tractor doing the work of eight mules in a hot 

desert valley 171 

52. Heavy plowing with an orchard tractor of the caterpillar 

type 173 

53. Substituting baled lima bean straw for manure in lemon 

orchard near Whittier, California ..... 176 

54. Cull oranges used as a humus-forming fertilizer . . . 180 

55. Canal lined with cement. Transformation of desert hills 

into orange groves ........ 187 

56. Preparing the ground for furrow irrigation. (From U. S. 

D. A. Farmers' Bui. No. 404) 190 

57. Irrigating stands in operation 194 

58. Zigzag furrows for wetting the ground between the trees . 197 

59. Overhead irrigation system in old orange orchard near 

Covina, California ....... 199 

60. King soil sampler. Of use when irrigating .... 202 

61. A well pruned Eureka lemon orchard. Photographed, 

August 10th, near Alhambra, California . . . 205 

62. Prototype of California pruning saw. From Volckamer's 

"Hesperides," 1708 207 

63. " California " pruning saw, used throughout southwest . 208 

64. Good type of pruning saw above ; poor type below . . 210 

65. One of the best types of pruning shears . . . .211 

66. Vigorous fruiting brush growing in the place of suckers . 212 

67. This extra vigorous shoot terminated at six inches with a 

fruit showing that excess of food did not change it into 

a sucker 214 

68. A sixty -acre three-year-old Valencia orchard top-worked to 

lemons. The paper bags protect the buds from rose 

beetles 215 

69. Fifteen months' growth on stocks shown at Fig. 68 . . 210 

70. Three-year-old Navel head on top-worked sweet seedling . 221 



xvm 



List of Illustrations 



71. Pruning a frosted lemon orchard 

72. A. Normal vesicles of lemon. B. Enlarged vesicles from 

frosted fruit six months after injury 

73. Frost splitting of bark on fruiting brush of lemon 

74. Three-year-old trees protected with cornstalks 

75. Screen of tobacco cloth as a frost protection 

76. Big six 

77. Eichhoff coal burner . 

78. Hamilton down-draught 

79. Bolton . 

80. Coe 

81. Pomona pipe-line heater 

82. Dunn ..... 

83. Canco 

84. Rayo 

85. Hislop ..... 

86. Hamilton reservoir 

87. Troutman .... 

88. Adamson torch . 

89. Coal-burning orchard heaters. 

trees .... 

90. Orchard heaters ready for lightin^ 

91. Orchard heaters in old Valencia grove 

92. Placement of orchard heaters. Extra fuel in 

trees 

93. The perforated stack gives good combustion but 

rainwater . . . . . 

94. The water separator for frosted fruit . 

95. Thermometer station of the Pomona Valley < >r 

tective Association 

96. Tuttle fruit clippers with rounded points 

97. Dashboard picking bag .... 

98. Covina picking bag 

99. Woodward picking bag 

100. The Wiss clipper now being superseded by 

shown at Pig. 96 . 

101. Metal attachment for propping up limbs 



Fuel stored in b 



may 



hard 



the ' 



under 

under 
admit 



Pro- 



"uttlt 



List of Illustrations xix 

FIG. PAGE 

102. Worm brushes used for polishing oranges .... 284 

103. Rope feed hopper 285 

104. Orange sizing machine ....... 286 

105. Box press and nailing machine 287 

106. Citrus fruit truck 288 

107. Packing stand ' . .289 

108. Box-squeeze, small size 290 

109. Car-squeeze, large size 291 

110. Interior view of the Pioneer Fruit Co.'s orange packing 

house at Lindsay, California 294 

111. Orange packers at work 296 

112. A typical orange box label 299 

113. General arrangement of orange packing house . . . 300 

114. Picking lemons ......... 302 

115. Two-story lemon packing house, Glendora, California . 304 

116. Lemon washing machine and sorting table .... 307 

117. Lemon curing tents in packing house near the coast . . 309 

118. Truck for handling trays of ungraded lemons . . . 310 

119. Packing lemons from sorting trays 311 

120. Lemon packing house, second floor and elevation . . 314 

121. Typical lemon box label 315 

122. Combination box label . . 316 

123. Fumigation scars . . . . . . . . 322 

124. Scar caused by rubbing on the ground .... 323 

125. Orange splits. Side splits above and Navel end splits below 327 

126. Horizontal cracks are very different from splits . . . 328 

127. Peteca of lemon 329 

128. The Fawcett method of treating gum disease. Note types 

of scrapers ......... 365 

129. Reddish gum areas on under side of leaves caused by 

sunburn ......... 368 

130. Exanthema pustules on Valencia orange twigs . . . 370 

131. Mottled-leaf disease on Eureka lemon .... 375 

132. Advanced stage of mottled-leaf disease showing multiple 

buds 377 

133. Spot caused by wither-tip 380 

134. A ".nest " of cottony fungus 384 



XX 



List of Illustrations 



FIG. PAGE 

135. Black rot of Navel ... .... 388 

136. Brown spot of Navel orange ...... 390 

137. Stem-end spot of orange 399 

138. Pruning stub on orange tree infected with schizophyllum . 400 

139. Black scale on orange twig 406 

140. The red scale on orange . . . . . . .411 

141. Work of red scale on orange tree . . . . . 413 

142. The purple scale enlarged ....... 416 

143. Cottony cushion scale 417 

144. Citrus mealy-bug 422 

145. Scars due to citrus thrips . . . . . . . 426 

146. Fuller's rose beetle 429 

147. The work of Fuller's rose beetle ...... 429 

148. Scars on rind of orange caused by katydid .... 430 

149. A fumigation demonstration ...... 432 

150. Method of marking fumigating tent 436 

151. Flashlight picture of marked fumigating tents . . . 442 



CITRUS FRUITS 



CITRUS FRUITS 



CHAPTER I 

HISTORY AND DEVELOPMENT OF THE CITRUS 

INDUSTRY IN THE SOUTHWESTERN UNITED 

STATES 

Citrus seeds were first brought into California from 
the peninsula of Lower California, where peoples of Spanish 
descent have cultivated various kinds of European fruit 
trees and vines since the year 1701. In 1768 the Jesuit 
missionaries were supplanted by the Franciscans, some 
of whom under the leadership of Junipero Serra pushed 
northward into the territory which is now the state of 
California. These hardy pioneers founded the first 
mission in Upper California at San Diego in 1769, and 
proceeding northward established a chain of missions 
extending four hundred miles along the coast, the last 
being established at Somoma in 1823. 

At a number of these missions, vineyards and orchards 
were planted. Cuttings of grapes and figs, and seeds of 
oranges, pomegranates, citrons, olives, pears, dates, and 
other fruits were brought from the older missions on the 
peninsula. At several missions the remnants of the old 
orchards may still be seen, partly inclosed by the adobe 
walls which were built to protect the trees from wandering 
herds of cattle. 

b 1 



2 Citrus Fruits 

The San Gabriel Mission near the present city of Los 
Angeles, by reason of the abundance of water and the 
large number of neophytes brought into service, gained 
rapidly in wealth and productiveness. The exact date 
when orange seed were first planted at this mission is not 
known, as the archives of the mission church are lost. It 
is certain, however, that the first California orange orchard 
of any size occurred at San Gabriel, and various writers 
agree that this orchard must have been planted in 1804 
or the following year. This first orchard covered about 
six acres of ground and was composed of about four 
hundred seedling trees, a few of which were still bearing 
in 1885. 

Although this orchard was not planted for financial 
gain, and it is doubtful if any fruit was ever sold from it, 
the success of this pioneer planting established the fact 
that the climate and soil conditions were quite favorable 
to the production of citrus fruits. 

Soon orange trees distributed from the missions began 
to be planted in court-yards and gardens in various 
places, the fruits being either all consumed at home or 
given away to friends. Perhaps the largest number of 
trees in any private garden were the thirty-five trees 
transplanted from San Gabriel about the year 1834 to 
Aliso Street in Los Angeles, by Don Louis Vignes. It 
remained, however, for William Wolfskill, a Kentucky 
trapper of German blood, who had come to Los Angeles 
overland in 1831, to forecast the commercial possibilities 
of this fruit. Wolfskill secured orange trees from the San 
Gabriel Mission in 1841 and planted a two-acre orchard 
in what is now the city of Los Angeles, on the spot now 



History and Development of the Citrus Industry 3 

occupied by the Arcade passenger station of the Southern 
Pacific Railroad. The fruit from this orchard sold to 
such advantage that it was increased in size to about 
twenty-eight and finally to seventy acres. It is said that 
Wolfskill was the first to ship a full car of oranges to 
Eastern markets. They were sent to St. Louis in 1877 
and arrived in good condition after having been a month 
in transit. The freight charge is said to have been $500. 
The last crop disposed of in his lifetime sold on the trees 
for $25,000. 

The success of the Wolfskill orchard stimulated others, 
and in 1853 Matthew Keller secured orange seeds from 
Central America and also from Hawaii. From these he 
raised young trees with which he planted an orchard 
opposite that of W T olfskill. In 1857 L. Van Leuven planted 
orange trees at Old San Bernardino, and in the same 
year L. F. Cram planted a small orchard at Highlands. 
Myron H. Crafts planted two hundred orange trees at 
■Crafton in 1865. 

In September, 1870, J. W. North of Knoxville, Ten- 
nessee, bought four thousand acres of desert land which 
is now occupied by the city of Riverside. Judge North 
carried on an advertising campaign in the Eastern states 
to attract colonists to this land. Settlers began to arrive 
the following winter, and in the spring of 1871 the first 
orange seeds were planted. 

This means of settling the country was used in various 
parts of California. Pasadena was first known as the 
Indiana Colony, the lands being purchased in 1873, 
distributed in 1874, and orange orchards planted as soon 
as the ground was leveled and irrigation water provided. 



Citrus Fruits 



Frank A. Kimball planted orange and lemon trees at 
National City in San Diego County about 1870. 

A large proportion of the trees planted at this time were 
purchased from the nursery of T. A. Garey in Los Angeles 
(Fig. 1). Garey imported a large number of varieties 

from various places 
during the years 1868 
to 1875. He is said 
to have received 
shipments of trees 
from Australia, 
southern Europe, and 
Florida, as well as 
from the nurseries of 
Ellwanger and Barry 
of Rochester, N. Y., 
and Sir Thomas 
Rivers of Sawbridge- 
worth, England. 

The fruit from 
these primitive or- 
chards was either 
consumed in the 
neighborhood of its 
production or hauled 
to Los Angeles and there shipped to northern ports by 
water. Southern California still lacked railroad connec- 
tion with the Eastern markets and there was no incentive 
to grow more oranges than sufficed for local consumption. 
Orange trees were first planted in the central and 
northern part of California in the early sixties. The first 




Fie 



1. — Thomas A. Garey, a pioneer 
citrus nurseryman. 



History and Development of the Citrus Industry 5 

planting of which we have record was at Bidwell in Butte 
County in 1859. In a great many cases these early 
plantings proved successful, and it was soon apparent 
that areas of greater or less extent, suitable for the 
growth of citrus fruits, existed in many scattered locations 
all the way from San Diego in the south to Shasta County 
in the north. 

The commercial development of citrus culture may be 
said to have begun with the completion of the Southern 
Pacific Railroad's connections with the East. The Valley 
line was completed in 1876 and the Southern line to New 
Orleans in 1881. The exhibition of the first fruits of the 
Washington Navel orange at Riverside gave another 
impetus to citrus planting, but the greatest development 
came with the completion of the Santa Fe's competing 
line of railroad, which was opened up about 1885. The 
first special train loaded exclusively with oranges left the 
River Station, Los Angeles, February 14, 1886, for the 
East via the Southern Pacific and Union Pacific Rail- 
roads. 

In February ,1879, what was probably the first of a series 
of annual citrus fairs was held at Riverside. The differ- 
ent citrus-growing communities of southern California 
took great interest in these fairs, and the prizes together 
with the prestige which they carried were vigorously 
competed for. It was at these early citrus fairs that the 
great superiority of the Washington Navel orange, the 
history of which is given on another page, became appar- 
ent. The climate and soil conditions in California proved 
eminently suited to this variety of orange, which here at- 
tained a perfection truly marvelous. The strong demand 



6 Citrus Fruits 

for these oranges in the Eastern markets and the high 
prices received by some brought on a period of frenzied 
planting and speculation. A great deal of worthless nurs- 
ery stock, quickly and cheaply grown on Chinese lemon 
roots, was planted, and many orchards were set out on 
lands more or less unsuited to citrus culture. This wave 
of rapid expansion culminated in 1885-86, when drouth, 
frosts, scale insects, and the lack of a coherent marketing 
organization conspired to rudely awaken from their 
golden dreams many who had rushed into the business with 
insufficient knowledge and capital to weather a period of 
depression. 

In 1884, at the Cotton Exposition held in New Orleans, 
the twenty varieties of oranges grown and exhibited by 
Riverside took first premium in competition with the 
world. This fact was heralded far and wide and proved 
of great value in advertising the California citrus business 
in general and Riverside in particular. 

In the early days of the industry there was no adequate 
horticultural inspection or quarantine service, and as a 
consequence a number of kinds of very destructive scale 
insect pests were introduced on nursery stock imported 
from various parts of the world. In this way the cottony 
cushion scale (Icerya purchasi) was introduced from 
Australia in 1868. In twenty years this scale spread 
throughout the orchards of Los Angeles County. So 
serious was this pest that the industry, in Los Angeles 
County at least, was on the verge of extinction. 

In the spring of 1888 Albert Koebele was sent to Aus- 
tralia by the U. S. Department of Agriculture to study 
the cottonv cushion scale in its native land. The follow- 



History and Development of the Citrus Industry 7 

ing year Koebele succeeded in introducing the Novins 
cardinalis, a small predaceous ladybird beetle, which at 
once attacked the scale and preyed upon it to such an 
extent that it was checked in its spread, and in many 
localities it was almost exterminated. As a consequence, 
in 1891, the shipments from Los Angeles County suddenly 
increased from 781 to 2212 cars, a net gain of 1431 cars, 
due, at least in large part, to the good work of the 
ladybird. Since the introduction of this predaceous 
beetle the white scale has been held in check and is not 
now feared by citrus growers. 

The fight with the cottony cushion scale had hardly 
been won, however, when other difficulties appeared. Al- 
though the orchards produced large crops it became more 
and more difficult to successfully market the fruit. The 
season of 1892-93 was particularly disastrous as far as 
net returns were concerned. The growers were not 
organized, and as long as each grower attempted to market 
his own fruit he became an easy prey to the miscellaneous 
assortment of commission men, agents, and speculators 
who at that time infested the markets and who in many 
cases, it is said, secured secret rebates from the railroads. 
In Riverside and in all the older sections, where there was 
any quantity of fruit to ship, account sales in "red ink" 
were received without number, and it frequently happened 
that the larger crop a grower had, the more he was in- 
debted to his packer at the end of the season. As a result 
of these failures to successfully market large crops, a few 
of the growers began to associate themselves together for 
mutual protection and to provide better packing facilities. 
Stimulated by the success of some of these associations in 



8 Citrus Fruits 

gaining concessions from the railroads and in many other 
ways securing better returns for their members, a large 
percentage of the growers assembled at the Chamber of 
Commerce in Los Angeles on April 4th, 1893, the declared 
purpose of the meeting being : "To provide for the mar- 
keting of all the citrus fruit at the lowest possible cost 
under uniform methods, and in a manner to secure to 
each grower the certain marketing of his fruit and the 
full average price to be obtained in the market for the 
entire season." At this meeting a cooperative packing 
and marketing organization was formed, which, while 
not entirely satisfactory, was a great improvement over 
the old methods and served to prepare the way for the 
Southern California Fruit Exchange, which was organized 
October 21, 1895. At first the Exchange handled about 
32 per cent of the total shipments, but the proportion 
of the crop handled has gradually increased till at the 
present time the Exchange ships about 62 per cent of the 
total crop. 

On March 27, 1905, the California Fruit Growers' 
Exchange was incorporated, and on September 1, follow- 
ing, succeeded to the business of the Southern California 
Fruit Exchange, this change in name being deemed 
advisable in order that the marketing organization itself 
might in name as well as in fact become general through- 
out the state rather than remain local to southern Cali- 
fornia. The Exchange is now an association of three groups 
or classes of organizations : the one hundred and fifteen 
local associations ; the seventeen district exchanges ; 
and the central exchange. For a detailed description 
of this rather complex organization see pages 345 to 353. 



History and Development of the Citrus Industry 9 



California Citrus Shipments 



Season 


Carloads 


Season 


Carloads 


Season 


Carloads 


1890-91 


4016 


1898-99 


10875 


1906-07 


29820 


1891-92 


4400 


1899-00 


18400 


1907-08 


32729 


1892-93 


5871 


1900-01 


24900 


1908-09 


40592 


1893-94 


5022 


1901-02 


19180 


1909-10 


32648 


1894-95 


7575 


1902-03 


23871 


1910-11 


46394 


1895-96 


6915 


1903-04 


29399 


1911-12 


40673 


1896-97 


7350 


1904-05 


31422 


1912-13 


18960 


1897-98 


15400 


1905-06 


27610 


1913-14 


48548 



Not the least important factor in building up the citrus 
industry has been the protective duties imposed upon 
citrus imports by the Congress of the United States. Such 
protective duties have prevailed since July 4, 1789, when 
a general tariff bill was passed which included a 5 per cent 
ad valorem duty on all citrus fruits. Since that time the 
duty has been gradually, though not uniformly, increased 
by the enactment at different times of nineteen changes 
in the law. By the Underwood-Simmons tariff act, effective 
October 4, 1913, the duty is one-half cent per pound on 
oranges, lemons, pomelos, and limes. Orange peel or 
lemon peel, preserved, candied, or dried, one cent per 
pound ; citron or citron peel, preserved, candied, or dried, 
two cents per pound. Citric acid, five cents per pound. 
Citrate of lime, one cent per pound. Orange and lemon 
oil, ten per cent ad valorem. Bergamot, neroli, or 
orange flower oil, twenty per cent ad valorem. The 
free list includes fruits in brine ; lemon, lime, and sour 
orange juice containing not more than two per cent of 



10 Citrus Fruits 

alcohol ; and orange and lemon peel not preserved, can- 
died, or dried. 

California citrus culture, among all horticultural in- 
dustries, is peculiar in that the people who have built 
it up have been, in many cases, retired business men or 
professional men from the New England and Central 
states. Persons who have lost their health in the process 
of gaining wealth have bought and developed citrus 
properties, the management of which, by requiring a life 
in the open sunshine and dry air, has resulted in renewed 
health and steadied nerves. These people brought to 
the industry much needed capital, commercial habits, 
and business ability. Citrus culture appeals to people 
of intelligence and refinement, and such are being drawn 
from many occupations. Now since the automobile 
has come into such general use, the wealthy business man 
of the city builds a residence in his orange orchard in the 
suburbs, while along the interurban electric lines may be 
found the small orchards of the superannuated minister, 
the retired high school teacher, the lawyer, the doctor, 
as well as of those drawn from other walks of life. 

The result of this has been the development of an in- 
dustry characteristically American in spirit and new in 
methods. The sons and grandsons of pioneers from the 
West and middle West have little regard for the precedents 
and practices of the Old World citrus-producing regions. 
European methods are practically ignored in systems of 
cultivation, irrigation, and pruning. In their readiness 
to organize among themselves along business lines and 
work together for the better picking, packing, and mar- 
keting of the fruit, the California citrus growers are 



History and Development of the Citrus Industry 11 

probably in advance of any other class of fruit growers 
on earth. 

The citrus industry has also been greatly benefited by 
various government agencies, whose endeavor has been to 
increase knowledge through scientific investigations and 
disseminate this new information through free lectures 
and pamphlets, by experiment farms, and by operating 
for months at a time free demonstration trains on the 
railroads. There have been three principal agencies 
engaged in this work : the University of California Agri- 
cultural Experiment Station, the United States Depart- 
ment of Agriculture, and the State Horticultural Com- 
mission. The university work may be said to have begun 
with the analyses of oranges and lemons in 1885 and con- 
tinued to date, covering a multitude of problems affecting 
the industry. The university conducts a special corre- 
spondence course on citrus fruits for the benefit of growers 
everywhere. The agents of the Department of Agricul- 
ture have rendered valuable service to the industry in 
many ways. The State Commission of Horticulture has 
done much good work in preventing the entrance into the 
state of new pests and checking the spread of pests al- 
ready introduced. It has distributed many valuable 
publications, the one prepared by Lelong 1 in 1902 being 
of special value to the industry. 

A large number of strong, loyal agricultural and horti- 
cultural periodicals throughout the state have broad- 
casted useful information and fanned the flame of popular 
interest. 

Still another upbuilding agency has been the Chambers 

1 B. M. Lelong, "Culture of the Citrus in California," 1902. 



12 



Citrus Fruits 



of Commerce in the various towns and cities. By main- 
taining interesting and attractive exhibits with free stereop- 
ticon lectures for visitors and tourists, and by preparing 
large exhibits for distant expositions, they have done a 
great deal to advertise the industry. 

Citrus culture in California will always be a popular 

occupation be- 
cause it appeals 
to a man from 
so many sides. 
It appeals to 
his love of the 
beautiful ; beck- 
ons him to health- 
ful outdoor life; 
stimulates that 
inborn desire in 
man to make 
things grow ; sat- 
isfies his appetite, 
and last, but by 
no means least, 
it tempts him 
with offers of large 
financial rewards. Successful citrus culture calls for a 
combination of the science and the art of horticulture ; 
requiring both skill and industry, it gives healthful occu- 
pation to the mind as well as the body. While a good 
many seedling orchards still persist in the older sections, 
they are gradually yielding (Fig. 2) to the activities of 
the woodchopper. 




Fig 



The passing of the 
orange groves. 



seedling 



History and Development of the Citrus Industry 13 



HISTORY OF THE WASHINGTON NAVEL OR BAHIA ORANGE 

The earliest illustrated description of a Navel orange 
on record was published in Rome by a monk of the Society 
of Jesus, John Baptiste Ferrarius, in 1646, in one of four 
books called "The Hesperides or About the Golden Apples, 
Their Culture and Use." The picture reproduced on page 
52 of Lelong's "Culture of the Citrus in California," 
from John Johnson's book, will be seen on close comparison 
to be an artful copy from Ferrarius. This was certainly 
not the Washington Navel as we have it to-day, but 
merely one of the many Navel forms which have ap- 
peared from time to time. It is not unlikely that still 
other kinds of Navels will appear in the future. 

Orange trees were taken to Brazil by the Spaniards 
at a very early day and were more or less widely planted 
in those parts of the country best suited to their culture. 
Some time about the year 1820 or possibly earlier there 
appeared near the village of Bahia a form of Navel orange 
which was remarkable for its many good qualities. This 
was what we now know as the Washington Navel. It was 
hastily propagated and planted to a considerable extent. 
Specimens were sent to London and the form became 
known abroad under the name Bahia, after the village where 
it originated. At Bahia it was called simply " Lavanja de 
Umbigo." 

Circumstantial evidence from several directions all 
points to the probability that from the very beginning 
one characteristic of this Navel orange was to produce 
occasional branches which bore fruit differing from that 
of the rest of the tree. In this wav a modified form came 



14 Citrus Fruits 

into existence, the fruit of which was scant in amount, 
large in size, with a coarse exterior, and interior full of 
rag. Unwittingly this form was propagated along with 
the true Bahia. After years of experience the best Brazil- 
ian growers became aware of this sporting habit and 
were careful to select buds for propagation from the best 
type only. The peasants, however, did not comprehend 
the situation, and as the demand increased, continued to 
cut bud wood indiscriminately. On account of the pub- 
licity given the fruit sent to London, a trade in nursery 
trees sprang up. Agents from Rio de Janeiro went to 
Bahia and secured what was available, including both 
the prototype and the false type. Thus it is natural to 
suppose that the stock on the Rio de Janeiro market 
must have consisted of some lots of Bahia, some of false 
Bahia, and some mixed lots. 

There is a tradition that this Bahia Navel was intro- 
duced into Florida some time previous to 1835, but that 
the trees were killed in the freeze of that year. It is said 
that the Bahia Navel was introduced into Cape Colony, 
South Africa, by a Mr. Brehm of Uitenhage about 1840. 
The subsequent record of these trees shows that Brehm's 
importation consisted entirely of the false form. On this 
account the Bahia was held in ill repute in South Africa, 
until between 1894 and 1900, when a number of importa- 
tions of the true Bahia were made direct from California. 
The fruit of these has been found equal in every respect 
to the best California product, and most of the old orchards 
have now been budded over. 

From Brazil the Sweet orange was first introduced into 
New South Wales, Australia, by Captain Hunter, who ac- 



History and Development of the Citrus Industry 15 

companied Gen. Arthur Phillip at the founding of the 
colony in 1788. 

Orange growers in Australia early introduced the Bahia 
Navel direct from Brazil. One writer in 1858 states 
that Navel oranges were for sale in Australian markets, 
and that they brought a much higher price than other 
varieties. I have been unable to discover the exact date 
of introduction, but oranges were exported in considerable 
amounts from New South Wales in 1860, and it is perhaps 
safe to assume that at least a part of these were Bahias, 
since a writer in the Victorian Farmer's Journal in 1862 
states that on account of the high prices received, the 
"Bahia Navel" was largely grown. From these state- 
ments it would seem that the date of the introduction of 
the Navel into Australia should be given as not later than 
1850. Australian writers are not unanimous in praise of 
the Navel and this indicates that both the true and the 
false form existed there as early as 1860. We may con- 
clude, therefore, that this orange was grown commercially 
and was marketed under the name of Bahia or Navel 
orange as early as 1860. 

S. B. Parsons, a nurseryman of Flushing, Long Island, 
owned a small nursery at Blue Spring, Florida. Wishing 
to secure this Bahia Navel for propagation and sale, he 
ordered trees in 1868 from Thomas Rivers, a large nurs- 
eryman of Sawbridgeworth, England, who had received 
his stock from the Azores, to which place they were said 
to have been brought from Brazil. (In all probability 
they were not.) This orange proved not to be the Bahia 
Navel, and has since been known as the Parsons Navel. 
Thomas Rivers also sold some of the same lot of trees to 



16 Citrus Fruits 

A. B. Chapman of San Gabriel, California, in 1870 or 1871. 
Some of these were propagated and sold by Mr. Chapman 
as the Rivers Navel. 

Thomas A. Garey, a well-known California nurseryman 
and author of a book on orange culture, 1 established a 
citrus nursery in Los Angeles in 1865. Some of his asso- 
ciates now living inform me that he imported citrus seeds 
and trees from Australia, Mexico, Central America, and 
southern Europe. He is said to have secured the Navel 
in 1870, and it is an open question as to where he got it, 
with the probability strongly in favor of Australia. I 
have a copy of his catalogue dated 1876, in which he lists 
it as "Bahia Navel," but cautions his customers against 
its shy bearing. Some persons who bought trees from 
him at that time condemn them as worthless, while others 
claim that they were identical with the Washington Navel. 
Garey must certainly have secured at least a preponder- 
ance of the false type of Navel. In 1873 J. C. Wallace 
of Los Angeles imported four Navel trees from Australia, 
all of which proved to be the false form and have been 
budded over. From this time this false form of Bahia 
Navel became known in California as the "Australian 
Navel" to distinguish it from the true Bahia. The 
Parsons Navel trees distributed by A. B. Chapman under 
the name of Rivers Navel also came to be known as 
Australians. In fact, any forms which differed from the 
true Bahia of the "Tibbet" tree type were very likely to 
be called Australians, and on account of this name they 
were supposed by many to have originated in Australia. 

1 "Orange Culture in California," by T. A. Garey, San Fran- 
cisco, 1882. 



History and Development of the Citrus Industry 17 

I can find no evidence whatever in support of the state- 
ment made by Lelong in 1888 that " The Australian Navel 
was introduced by Louis Wolf skill in 1874." The success- 
ful importation of the true Bahia took place as follows : 

In 1870 William Saunders, then in charge of the govern- 
ment propagating grounds at Washington, D. C, through 
the assistance of a lady missionary stationed at Bahia, 
Brazil, had twelve trees of the Bahia Navel orange propa- 
gated and sent to Washington in tubs. All twelve of these 
were true Bahia, and after being placed in the greenhouse 
at Washington were used indiscriminately as a source of 
buds from which were propagated a number of trees for 
distribution, many of which were later sent to Florida and 
California. All twelve of these original trees for some 
reason passed out of existence. The first lot propagated 
was distributed to California and Florida, and one tree 
from this lot was planted in the orange house at Washing- 
ton, where it still remains. The common idea that this 
tree in Washington is the original tree imported is wrong. 
It was propagated from one of the original twelve. 

The active settlement of Riverside, California, began 
about 1870, and was extensively advertised in the East 
by Judge North, the founder of the Colony. Among other 
settlers attracted were Luther C. Tibbet and wife. Early in 
1873 Mrs. Tibbet (Fig. 3) was in Washington just previous 
to starting to her new home at Riverside, California. Wliile 
visiting the government propagating gardens, Mr. 
Saunders offered to give her some trees of this Bahia 
orange and she gladly accepted two trees, which she carried 
to California, where she and her husband planted them 
beside their cottasre in Riverside on land which thev had 



18 



Citrus Fruits 



homesteaded. According to present street nomenclature 
the spot formerly occupied by the Tibbet cottage is on 
Central Avenue near Palm Avenue. The fruit from these 
trees first attracted attention at a private meeting of 

fruit growers in the 
winter of 1877-88, at 
which time the Navel 
trees sold by Thomas 
A. Garey had been in 
bearing several years. 
In February, 1879, 
the Southern Cali- 
fornia Horticultural 
Society (J. De Barth 
Shorb, President, and 
L.M.Holt, Secretary) 
held a citrus fair at 
Riverside. At this 
fair Mr. T. D. Cover 
exhibited fruit from 
the Tibbet trees and 
was awarded first 
prize over other 
Navels exhibited 
from Orange County, 
which came from 
trees imported from Australia by Mr. Garey. The 
difference between the two forms was recognized by ex- 
pert fruit growers; the Tibbet oranges being called 
Washington Navels because Mrs. Tibbet, probably for- 
getting the name "Bahia," always said in answer to in- 




Fig. 3. — Mrs. L. C. Tibbet, who first 
brought the true Navel orange to Cali- 
fornia. 



History and Development of the Citrus Industry 19 

quiries that the trees came from Washington. All other 
kinds of Navels were called Australians because it was 
supposed that they all came from Australia. 

A. S. White of Riverside writing in the Riverside Press 
and Horticulturist under date of June 26, 1880, says, — 
" It (Washington Navel) was first exhibited at the River- 
side Citrus Fair last year (1879), where it attracted great 
attention, its appearance being so unlike the other Navels 
on exhibition, which were from the stock imported into 
California from Australia. The marked points of differ- 
ence between the two Navel oranges lie in their external 
appearance. Instead of being like the Australian, ribbed 
lengthwise, it is smooth and more globular. The skin 
is of a finer texture, has more of a satin-like appearance, 
and shows a much higher color, being of a bronzy-gold 
tint." 

An editorial (presumably by L. M. Holt) in Riverside 
Press and Horticulturist, in 1883, says : " We have but 
two varieties as yet of the so-called Navel orange. The 
first was introduced into California from Australia. 
Both varieties, the Washington and Australian Navels, 
are now being grown quite extensively though the trees 
are young yet, and I must confess it is at times a puzzle 
to distinguish one from the other, under test conditions, 
and I believe I am not alone in this position." 

After studying a number of the discussions in the early 
literature, the writer is of the opinion that since both the 
true and false form of Bahia orange existed in Australia, 
that T. A. Garey's original importation in 1870 was mixed 
and that at least some trees sold by him were the true 
Bahia. How else can we account for the fact that cer- 



20 Citrus Fruits 

tain reputable and apparently experienced men insisted 
for years that some of the trees sold by Garey bore fruit 
identical with that of the Tibbet trees at Riverside. If 
this is true, then the Tibbet trees were not the first genu- 
ine Bahia Navels to reach California. It is a fact beyond 
dispute, however, that the Tibbet trees are the ones 
which attracted attention and were undoubtedly the 
direct cause of the great boom in the orange growing 
business which began in the early 80's. 

Giving Mrs. Tibbet two trees, Mr. Saunders sent several 
trees to Florida and some to California. Alexander Craw, 
then foreman for J. M. Asher, a nurseryman of San 
Diego, is said to have received two of these trees. It 
might be argued that Mr. Garey secured his stock of Bahia 
from Craw or even from Mr. Saunders at Washington. 
This is barely possible, but in view of the shortness of 
time thus allowed to work up the stock, and the letters 
of his contemporaries stating the contrary, it is hardly 
probable. 

For two or three years after the Tibbet trees began to 
be propagated in Riverside this orange was known as the 
Washington Navel. In 1883, however, a determined 
effort by the people of Riverside was made to change the 
name to Riverside Navel in order (according to L. M. Holt 
in Ontario Fruit Grower, May 16, 1883) that Riverside, 
the town where this variety happened to be first tested, 
might get the benefit of the advertising which would 
follow the use of this name. O. H. Conger of Pasadena 
and others vigorously opposed this to such good purpose 
that the name Riverside Navel became a synonym. 

Luther C. Tibbet is known to have been rather improvi- 



History and Development of the Citrus Industry 21 

dent. He never owned any orange trees other than the 
two his wife brought from Washington. He permitted 
his homestead to pass out of his hands, but he and his wife 



■' c ' 



IkM 





Fig. 4. — One of the original Washington Navel orange trees brought 
to California. 



were allowed to live in the cottage during the life of Mrs. 
Tibbet. After her death Tibbet was cared for at the 
County Hospital until he died July 1, 1902. 

In 1903 Louis Jacobs was the owner of the Tibbet 



22 



Citrus Fruits 



homestead. He gave one of the trees to Frank A. Miller, 
proprietor of the Glenwood Hotel, who had it removed 
to its present location in front of the hotel May 7, 1903. 
President Roosevelt, a guest at the hotel at the time, 
assisted in transplanting this tree, for the care of which 
Mr. Miller is now responsible. 

Citrus Acreage in Counties in California having more 
than 10,000 Trees in 1910 



County 



Los Angeles . . 
San Bernardino 
Tulare . . . 
Riverside . 
Orange 
Ventura 

San Diego . . 
Butte .... 
Santa Barbara . 
Fresno .... 
Kern .... 
Sacramento . 
San Louis Obispo 
Placer .... 
Yolo .... 
Glenn .... 
Tehama 
Sonoma 

Colusa .... 
Solano . . . 
All other counties 
Total for state 



Number of 

Trees 



3,283,500 


43,780 


3,149,250 


41,990 


2,985,000 


39,800 


1,966,705 


25,222 


1,149,605 


15,328 


503,137 


6,708 


395,974 


5,279 


146,673 


1,957 


144,270 


1,924 


106,928 


1,746 


78,500 


1,033 


55,780 


744 


39,000 


520 


33,115 


441 


18,575 


247 


16,540 


221 


13,565 


180 


11,270 


150 


11,000 


146 


11,000 


147 


56,797 


754 



14,176,184 



Acres 



188,317 



History and Development of the Citrus Industry 23 

About the same time the other original tree was given 
to the city by Mr. Jacobs and it was transferred to 
a small plot of ground at the head of Magnolia Avenue. 
J. H. Reed, then tree warden of Riverside, placed a 
substantial ornamental iron fence around it which affords 
protection from any thoughtless or selfish person. The 
city of Riverside is responsible for the care of this tree. 
Both the original trees are at this date in a healthy and 
flourishing condition, and the one on Magnolia Avenue 
especially is producing fair crops (Fig. 4). 

CITRUS GROWING IN ARIZONA AND SONORA 

The citrus industry of Arizona is hardly more than 
twenty-five years old, although occasional orange trees 
may have been planted at a very much earlier date. The 
first plantings of any importance were along the Arizona 
Canal west of Scottsdale in the Salt River Valley. The 
Ingleside orange grove on the foothills of Camel's Back 
Mountain was the largest of these early plantings, and it 
was due largely to its success that the acreage was in- 
creased in this locality. 

Another important prospective citrus area is on Yuma 
Heights near Yuma, where an old orchard ten or twelve 
acres in extent has served for many years to indicate the 
possibilities of this area. The lack of water develop- 
ment has been the chief hindrance to the planting of 
additional acreage. 

While California received its first orange seed from 
Sonora, this country has been very backward in its citrus 
development, chiefly for the reason that it has been 



24 Citrus Fruits 

isolated from home markets and handicapped by the 
tariff in reaching American markets. 

Geographically Sonora belongs to the Arizona and south- 
eastern California areas as the climate and soil conditions 
are very similar. The chief commercial orchards are 
situated near Hermosillo, in the valley of' the Sonora 
River, and near Guaymas. The production of fruit at 
Guaymas was greatly reduced in 1905 by a serious in- 
festation of the red scale. The variety chiefly grown at 
Hermosillo is the sweet seedling orange. The production 
gradually increased and in 1908 about 250 cars were 
sent in bond through the United States to Canada, which 
they enter duty free. 

The oranges produced in southern Mexico, especially 
in the states of Jalisco, Morelos, and San Luis Potosi, 
where the climate is more tropical, differ in character 
from those grown in Sonora, being inferior for shipping. 
Much of southern Mexico is infested with the Morelos 
orange maggot, Trypeta ludens, and this interferes with 
the marketing of the fruit. 



CHAPTER II 

CITRUS GEOGRAPHY AND CLIMATOLOGY OF 
CALIFORNIA 

Citrus fruits originated in India and the Malay Archi- 
pelago and are generally regarded as tropical fruits, yet 
it is a curious fact that the greatest commercial success 
with them has been obtained in semitropical countries. 
This statement applies especially to oranges and to a less 
extent to limes and pomelos. The bulk of the oranges 
which supply the markets of the world are produced in 
countries which experience a certain degree of frost, such 
as California, Spain, Florida, Palestine, Australia, Japan, 
and Italy. Oranges grown in moist tropical coun- 
tries are lacking in tartness, color, shipping and keep- 
ing qualities. All of these qualities, so desirable in a 
marketable orange, become more marked as we approach 
the line w T here frequency of frosts makes the culture of 
the trees unprofitable. 

The citrus producing lands of California are scattered 
from San Diego to Shasta County, a north and south dis- 
tance of four hundred and fifty miles. It is a peculiar 
fact that there are orange orchards in California in the 
same latitude with New York City and Lincoln, Nebraska. 
This is made possible by the peculiar topography of the 

25 



26 Citrus Fruits 

state, whereby the mountain ranges are so situated that 
the cold winds of the north are shut out from interior 
valleys, and the full effects of the abundant winter sun- 
shine allowed to accumulate. Along the southern coast 
also the mild moisture laden breezes from the Pacific 
modify the climate of the country between the mountains 
and the sea without interference from northern blasts, 
which are diverted eastward by the mountain barrier in 
northern California. From the point of view of the 
fruit grower, longitude is more important than latitude. 
Fig. 5 shows the distribution of the citrus areas of 
California. 

CLASSIFICATION OF CITRUS AREAS 

The areas where climatic conditions permit the growth 
of citrus trees may be roughly grouped into three divi- 
sions and designated as the Southern Coast, Interior 
Valleys, and Northern Coast Divisions, in the order of 
their importance as citrus producing areas. 

The Interior Valleys Division includes the Sacramento, 
San Joaquin, Upper Santa Ana, Coachella, Imperial, and 
Colorado Valleys and embraces all the country not imme- 
diately adjacent to or within the influence of the ocean. 
The Southern Coast Division includes all the citrus 
country between the mountains and the sea as far north 
as Santa Barbara. The Northern Coast Division includes 
all the country within the influence of the sea from Santa 
Maria as far north as northern Sonoma County. The 
amount of rainfall varies much in different parts of the 
state, but the rainy season is fairly uniform, being from 
November to March inclusive throughout each of these 



POSSIBLE AREA 
PLANTED AREA 




p . CO-*"' 



Fig. 5. — California citrus areas. 



(27) 



28 Citrus Fruits 

areas. Rainfall in the summer is very rare and thunder 
and lightning exceedingly rare especially near the coast. 
As the citrus industries of these three divisions differ 
in many particulars, we will discuss each division sepa- 
rately. 

The Southern Coast Division 

The climate of this section is characterized by an equa- 
ble temperature with cool summers and w T arm winters. 




Fig. 6. — Four-year-old Valencia orange grove in Los Angeles County. 

The rainfall is about 18 inches in the northern but de- 
creases in the southern part. The air is quite moist as 
compared with the interior, and there are frequent fogs 
and overcast skies. The prevailing breezes are from the 
Pacific Ocean, which has a surface temperature not far 
from 60° F. at all seasons of the year. The extent of the 
ocean influence depends upon local topography, being 
narrow in Santa Barbara County and widening out 
toward the south and including the San Gabriel Valley 
which contains the most highly developed and largest, 



Citrus Geography and Climatology of California 29 

contiguous citrus area in the state. Fig. 6 shows a 
representative orange plantation in southern California. 

In general, the soils of this region are deep and very 
fertile, being heavier near the coast and lighter in charac- 
ter toward the interior. The two prevailing soil types 
are the Placentia series, resulting from the weathering 
of reddish granite, which outcrops at many places, and the 
Maricopa series, which are alluvial in nature, being an 
ancient flood plain. These latter soils are darker in color 
and often contain smooth cobbles and bowlders invariable 
amounts. Less important soil types are the black adobe 
sometimes found on the foothills and the light sandy 
soils of the river bottoms. 

While the prevailing breezes are westerly, this section of 
country is occasionally visited by characteristic hot 
northers which blow with force for several days at a time 
from the northeast. At such times the air becomes 
excessively dry and high temperatures prevail. Such 
desiccating winds are sometimes quite injurious to vege- 
tation and cause a severe loss of water from plants and soil. 
It is fortunate that such winds are not of more frequent 
occurrence. 

The southern coast is especially adapted to the growing 
of lemons, which here produce a larger proportion of high- 
priced summer fruit. Stored lemons also keep better and 
expensive storehouses are not needed as is the case in 
interior valleys. The cool summers also make it possible 
to hold Valencia oranges on the trees until the follow- 
ing October and November, when very high prices are 
often realized. This section of country is also well suited 
to the production of nursery stock, which is grown in very 



30 Citrus Fruits 

large quantities, the San Gabriel Valley being the center 
of this industry. 

The Washington Navel orange here produces very 
heavy crops, but the fruit ripens later and is somewhat 
inferior to that produced in interior valleys both as re- 
gards color, texture, flavor, and shipping qualities. 

The Interior Valley Division 

The climate of all the interior valleys is characterized 
by conditions more or less extreme. The air is nearly 
always dry and this permits rapid radiation, causing a 
wide range in temperature each day. Rainfall is fairly 
abundant in winter in the northern valleys and less so 
toward the south. The air is free from fogs and dew in 
summer and constant sunshine is the rule. The days 
are often very hot, w r hile the nights are always cool. 

The floors of the valleys are, as a rule, frosty in winter 
and on this account the principal citrus areas are found 
along the foothills, above the frost line, and where irriga- 
tion water is available. Such- areas are usually at an eleva- 
tion of from 500 to 1500 feet above the sea, and from 100 
to 500 feet above the floor or "draw" of the valley. In 
such locations a few feet in the perpendicular is of far 
greater importance to the citrus grower than many miles 
in the horizontal. That is to say, whether the orchard 
is planted in a "draw" or on a bluff above it, yet on the 
same ranch, may mean more for the success or failure of 
the grove than whether the trees are planted near Holt- 
ville or at Oroville five hundred and fifty miles distant. 
Cold air is heavy and on quiet nights flows down and col- 



Citrus Geography and Climatology of California 31 

lects in the lowlands, leaving the foothills above the frost 
line. 

In the central valleys oranges ripen very early and 
as some of these are far to the north of the Coast Coun- 
try, the unusual procedure of shipping earliest ripening 
fruits southward to market is accounted for. 

The largest producing district in this division lies on the 
eastern foothills of Tulare County, including Woodlake and 
Porterville, at an elevation of four or five hundred feet 
above sea-level. One of the typical soils of this district 
is known as the Porterville clay loam adobe, which is a 
residual soil characteristic of the higher foothill slopes. 
Lower down the valley slopes are found soils of the San 
Joaquin series, which are sometimes characterized by 
"hog-wallows" and a certain amount of hardpan. The 
valley floor is composed mostly of alluvial soils of the 
Hanford series. 

In the northern Sacramento Valley the soils are very 
variable, but are mostly of a reddish color. They are in 
large part sedimentary soils of the San Joaquin, Stockton, 
Alamo, and other series. While there are many exceptions, 
it is true that these soils, especially on the east side of 
the* valley, are quite generally underlaid by a stratum of 
dense, impervious hardpan which occurs at variable 
depths. Where hardpan is near the surface, the land is 
not suited to citrus fruits unless it be dynamited and the 
hardpan thoroughly broken up. 

The Northern Coast Division 

In outline this division is very irregular, consisting in 
places of a narrow strip between the mountains and the 



32 Citrus Fruits 

sea and extending occasionally into valleys where the hills 
are low and do not entirely shut off the cool, moist sea- 
breezes. East of the bay region the coast influences 
extend far inland, following the Sacramento River and 
tempering the climatic conditions at the junction of the 
San Joaquin and Sacramento Valleys to such an extent 
that the region between the cities of Stockton and Sacra- 
mento is really intermediate in climatic characteristics. 
The climate of the Northern Coast forms a strong con- 
trast with that of the interior valleys. It is comparatively 
free from extremes of temperature, being warm in winter 
and cool in summer. The winter rainfall is usually heavy 
and there is much fog in summer. Here green, grass- 
covered hills are the rule instead of the bare rocky buttes 
of the interior. 

There are no large commercial citrus areas within this 
district, yet oranges and lemons are grown in yards and 
gardens and the product is used for local consumption 
throughout the district. The total amount of summer 
heat is small, and oranges do not yield well as a rule nor 
is the fruit high in sugar content. The color also is poor 
on account of the lack of abundant sunshine, and the trees 
are subject to the ravages of many insect pests and fungous 
diseases w T hich are not able to survive the hot summers 
of the interior valleys. The trunks and branches of trees 
on the coast are apt to become covered with a growth 
of lichens and alga? which should be removed with alkali 
sprays. 

The soils of the coast country are chiefly deep rich 
residual soils formed by the gradual weathering and 
breaking down of the local rock masses. 



Citrus Geography and Climatology of California 33 

THE FROST HAZARD 

It has been asserted that certain districts in California 
are free from frost. This is hardly true, for a certain 
frost hazard exists in all districts both north and south. 
Almost all districts on the other hand embrace certain 
areas which are comparatively frost free. One thing 
which usually impresses the stranger from the East most 
forcibly is the sharpness with which the frost lines are 
drawn. There are many ranches of a hundred acres or 
less which are divided by these frost lines into citrus 
lands, walnut lands, and alfalfa lands. It is often very 
difficult to accurately judge the frost hazard on any given 
piece of land unless there be an old orchard alongside 
upon the history of which, together with the local topog- 
raphy, an estimate may be based. Failures due directly 
to faulty judgment in regard to the frost hazard are almost 
without number. 

In recent years the science of orchard heating as de- 
scribed in Chapter XIV has enabled growers to insure 
their crops against occasional frosts, but where orchards 
must be heated many nights each winter the expense is 
quite likely to interfere with the profits. 

We may conclude then that throughout the citrus divi- 
sions of the Southwest there are specially favored dis- 
tricts where citrus fruits grow to perfection and are seldom 
injured by cold. Within each of these districts, however, 
there are many localities of irregular outline and extent 
which on account of local topography are quite out of the 
question as citrus lands. On this point Lelong x writes as 
follows : 

1 "Culture of the Citrus in California," 1902. 



34 Citrus Fruits 

"Wherever cold currents of air from high altitudes 
flow to the valley without interruption, it will not be safe 
to attempt citrus culture at any elevation within the sweep 
of these currents. On the other hand, wherever the 
descending currents are cut off or turned aside by spurs 
of the mountains, leaving the warm atmosphere of the 
days undisturbed during the nights, there orange and 
lemon culture may be engaged in with little danger from 
frost. In other words, the eddies of air currents must be 
selected and the main flow of these currents must be 
avoided. 

" Everybody who has traveled along the Sierra foothills, 
parallel with the valleys, particularly in the winter season 
and at night, will recall his surprise at the sudden changes 
of the temperature of the atmosphere within short dis- 
tances. He may also remember to have noticed tender 
plants and shrubs seared and frost-bitten, while just over 
a ridge or cone the same plants and shrubs were in full 
leaf and growing luxuriantly. Want of attention to these 
facts has caused many a disastrous failure in the culti- 
vation of citrus fruits in California." 



ATMOSPHERIC HUMIDITY 

In the interior valleys which are fanned by dry desert 
breezes, the amount of atmospheric moisture is very low, 
and this together with the great heat tends to produce 
oranges of high sugar content and with very desirable 
deep red color. Dry air also discourages the growth 
of certain diseases affecting the tree, as well as certain 
scale insects, lichens, and algee which cannot endure the 



Citrus Geography and Climatology of California 35 

desert conditions. On the other hand, lemon trees under 
such climatic conditions tend to bear only one crop a year, 
and the proper curing and keeping of lemons is made 
more difficult. The moist and foggy coast country with 
its cool sea breezes brings about a somewhat different 
phase of the industry. Here lemons tend to bear a con- 




Fig. 7. — Typical scene in Los Angeles County. 
robusta on right. 



Windbreak of Grevillea 



tinuous crop the year round, and the fruit may be easily 
stored in open sheds and kept in good condition for six 
or eight months. Oranges near the coast are six or eight 
weeks later in ripening than those of the interior, and the 
trees are subject to a larger number of the insect pests 
and diseases to which the citrus tree is heir. 



36 



Citrus Fruits 



WINDS 



Strong winds are a serious hindrance to the citrus 
grower. The young foliage is badly torn or may even be 




N>fc^u* 



' 




Fig. 8. — Pinus radiata, a native pine used as a windbreak. 

blown from the trees ; the fruit is bruised, scarred, and 
covered with unsightly callous marks ; the trees are pre- 
vented from forming symmetrical heads ; and in some 
cases the soil itself is either blown away from the roots 



Citrus Geography and Climatology of California 37 

or banked too deep around the trunks of the trees. In 
some extreme cases, the traveling sand wears away the 
bark of young trees near the ground. As a rule, windy 
locations should be avoided in selecting a site for a citrus 




Fig. 9. 



Orange tree denuded of foliage on windward side by three 
days of desert wind. 



orchard. In some cases, however, where all the other 
conditions are right, the force of the wind may be broken 
by growing windbreaks of cypress, eucalyptus, or cedar. 
Care should be exercised that the windbreak is not 
allowed to grow too thick and become a "wind-stop," 



38 Citrus Fruits 

as this may interfere with atmospheric drainage and make 
a frost pocket of the grove. A live windbreak is ob- 
jectionable on the ground that the roots appropriate the 
plant food and water from one or two rows on either side 
and seriously interfere with the fruiting of the orchard 
trees. This trouble may be obviated to some extent by 
digging a trench ten feet from the windbreak and three 
feet deep every second year and cutting all the feeding 
roots. Care should be used in selecting varieties of trees 
for windbreaks that they may not be host plants for 
insects which affect citrus trees. The pepper tree, 
Schinus molle, for example, makes an excellent wind- 
break and is largely used in interior valleys where the 
black scale is of less importance. Near the coast such 
trees may have to be fumigated occasionally at great 
expense. Figs. 7 and 8 show windbreaks of the silk oak 
(Grevillea robusta) and Monterey pine (Pinus radiata), 
which are much used in parts of California. Fig. 9 il- 
lustrates the damaging effect of the wind. 

SUNLIGHT 

While a certain amount of sunlight is absolutely neces- 
sary for plant growth, there are places in California where 
citrus plants are over-illuminated. Sunburn of the 
fruit and tree trunks and even of the leaves often occurs 
in the dry interior valleys, where the lack of moisture in 
the air permits the actinic rays of the sun to strike the 
trees with full force. In such situations, the fruit borne 
on the outside of the trees and fully exposed to the light 
is inferior and often ruined, while the fruit which is 



Citrus Geography and Climatology of California 39 

screened by foliage may be of the very finest quality. It 
is the custom among nurserymen to shield citrus seedlings 
from the light by growing them, for the first six or eight 
months, under lath screens so arranged as to reduce the 
total light about 75 per cent. Running the lath north 
and south will provide alternating light and shadow 
for any given seedling as the sun moves from east to west. 



'7 



CHAPTER III 

CITRUS BOTANY, GROSS STRUCTURE, AND 
HABITS OF GROWTH 

Citrus fruits differ from olives, figs, dates, and pome- 
granates in being of comparatively modern origin. They 
emerged from the wild state in the Malay Archipelago 
and southern Asia. Certainly citrus fruits were not 
known by civilized peoples until comparatively recent 
times. The ancient Egyptians did not know the citrus 
fruits. The Romans did not know the orange or any 
other edible form except perhaps the citron at the be- 
ginning of the Christian Era. 1 While the Old Testament 
makes frequent mention of olives, pomegranates, figs, and 
other fruits, no mention is made of any citrus fruit unless 
we except the word "hadar" translated "goodly trees" 
(Leviticus 23 : 40) as referring to the citron. Risso, 2 one 
of the most able of the early writers on citrus, compared 
the ancient texts and claims that this word merely refers 
to any beautiful or fine tree. It is likely that the 
Hebrews became acquainted with this fruit at the time 
of the Babylonish captivity. Be this as it may, the 
Jews believe this word refers to the citron, or etrog as 

1 De Candolle, "Origin of Cultivated Plants," p. 181. 

2 Risso and Poiteau, "Histoire Naturelle des Orangers." 

40 



Citrus Botany, Gross Structure, and Habits of Growth 41 

it is called by them, and to this day they present them- 
selves at the synagogue on the day of the Feast of 
Tabernacles, as commanded in Leviticus, with a citron 
in their hands together with an unopened date palm 
leaf, a three-parted branch of myrtle, and a willow twig. 

The citron, known by the Romans as Malum persicum, 
the apple of the Persians, was transplanted to Italy about 
the third or fourth century. 

The lemon was not brought to southern Europe until 
after the tenth century, and the earliest Italian reference 
to it is dated 1250 a.d. 

The bitter or sour orange was unknown to the early 
Greeks and Romans. It probably originated in eastern 
India and spread westward slowly. When it reached 
Mesopotamia it received the Sanskrit name nagarunga, 
which was changed to verunga and arangi. In medieval 
Latin it became arancium and finally aurantium, the present 
Latin name from which our English word orange is de- 
rived. The Crusaders saw the bitter orange in Palestine. 
It was taken by the Arabs to Sicily in 1002, spread from 
there to Spain, from whence it was taken to Florida soon 
after the settlement of that Colony. In Florida the bitter 
or sour orange ran wild, and dense thickets exist there 
to-day which yield the greater part of the sour orange 
seeds planted by California nurserymen. 

It is most remarkable that so good a fruit as the sweet 
orange should not have been known to ancient writers, 
yet they make no mention of it. In fact the sweet orange 
was not introduced into Europe until the beginning of 
the fifteenth century, when the Portuguese brought im- 
proved forms of it from south China. A number of writers 



42 Citrus Fruits 

speak of the sweet orange as cultivated in Spain in the 
sixteenth century. At a very early date the Portuguese 
carried the orange to Brazil, where it ran wild as it did in 
Florida. From Brazil the orange spread southward into 
Paraguay, part of Uruguay, and northern Argentina 
where large areas are now covered with a natural growth 
of wild sweet orange trees. 

CLASSIFICATION 

The genus Citrus belongs to the family Rutacece and rep- 
resents the highest development within the family. There 
are no species of citrus native to either North or South 
America. A relative is the prickly ash or " toothache 
tree," Xanthoxylum americanum, of the southeastern 
United States. 

No two systematic botanists appear to be agreed as to 
the proper classification of the many different species. 
This is probably due to the fact that several of the species 
hybridize readily and it is very difficult to determine 
which of the forms are of hybrid origin. The writer makes 
no pretense to having solved this perplexing problem by 
independent botanical research. He has simply studied 
the different schemes proposed and from them arranged a 
practicable, working classification for the use of students, 
fruit-growers, and others who desire a simple bird's-eye 
view of the ten species in which they are chiefly interested. 

Persons particularly interested in citrus botany are 
referred to Hume, " Citrus Fruits and their Culture " ; 
to Bonavia, "Oranges and Lemons of India"; and to 
Swingle, "Citrus" in "Bailey's Standard Cyclopedia of 
American Horticulture." 



Citrus Botany, Gross Structure, and Habits of Growth 43 



Citrus 



trifoliata 

bergamia, 

sinensis, 

Aurantium, 



nobilis 

decumana, 

japonica, 

Medica, 

Limonia, 

aurantifolia, 



j the deciduous orange (Poncirus tri- 
\ joliata) . 

Bergamot orange. 

common sweet orange. 

sour stock, Seville, or bitter orange. 
[ the King orange. 

J Var. deliciosa — the Mandarin or kid- 
glove orange. Tangerine. 
I Var. unshiu — the Satsuma orange. 

the pomelo (grapefruit), shaddock. 

kumquats. 

citron of commerce. 

sour lemon, sweet lemon. 

sour lime, sweet lime. 



All of these ten species are now grown, to some extent 
at least, in California, although some of course are very 
much more important than others. 

Citrus trifoliata. — This is the only deciduous orange. 
The fruit is not edible. It is highly ornamental and very 
hardy to cold, being used in yard and garden plantings and 
for hedges as far north as Washington, D. C. It is used to a 
certain extent in Florida and more generally in Texas as a 
stock upon which to bud edible oranges. Its use as a stock 
in California was never widespread, and is now almost obso- 
lete. Citrus trifoliata has recently been used to a considerable 
extent in breeding work, the object being to combine the cold 
resisting qualities of the trifoliata with the good qualities 
of the more tender species which bear edible fruit. It is 
native to Japan and China and was introduced into Europe 
more than one hundred years ago. This species is now by 
some put in the genus Poncirus, becoming P. trifoliata. 

Citrus bergamia. — The Bergamot orange from which the 
oil of bergamot is made is grown commercially in Europe. 
In California it is grown only as an occasional specimen or 
as a hedge plant in gardens. 



44 Citrus Fruits 

Citrus sinensis. — The ordinary sweet oranges including 
such varieties as Washington Navel, Valencia, Mediterra- 
nean Sweet, Ruby Blood, and a long list of others. 

Citrus Aurantium. — This is the sour or bitter bigarade 
orange, the fresh fruit of which is hardly edible, but which is 
coming to be used more and more in the flavoring of marma- 
lades and various other by-products. Seedlings of this orange 
have almost entirely superseded others as a stock upon which 
to grow all kinds of citrus fruits in California. The reason 
for this is its superior resistance to gum-disease and foot-rot. 
The seed from which this "sour stock" is grown comes 
chiefly from the wild thickets in Florida. In Europe this 
form is often called the Seville orange. 

Citrus nobilis. — The description of this species was based 
on a form very like the King orange. It includes the var. 
deliciosa, the ordinary Mandarin oranges such as the Tan- 
gerine and the var. unshiu, which is the Satsuma orange. 

Citrus decumana. — Here are included the pomelos, often 
incorrectly called "grapefruit," 1 and the shaddock. They 
are vigorous growing trees with very dark green leaves, very 
prolific in bearing. The pomelo is growing rapidly in public 
esteem, but the shaddock is inedible. The shaddock is the 
largest of all the citrus fruits, but has an extremely thick 
skin and bitter juice. It is the only citrus which has hairs or 
pubescence on the young twigs and under sides of the leaves, 
and is grown only for ornament or curiosity. 

Citrus japonica (recently referred to the genus Fortunella). 
— The Kumquats, Kin-Kans, or golden oranges, small 
bushy plants from Cochin-China. The fruits are small, with 
mostly acid pulp and sweet aromatic rinds, for preserving 
and for decorations. 

1 The term "grapefruit" has, chiefly through the influence of 
"the trade," become adopted by common usage, and it is hardly 
worth while now to insist on the use of the more correct term. 



Citrus Botany, Gross Structure, and Habits of Growth 45 

Citrus Medica. — The citron from which the candied 
citron sold by grocers is made. The form known in Cali- 
fornia as the Chinese lemon and much used in the early 
days as a stock is thought to belong here. 

Citrus Limonia. — The lemons including both the sour 
lemons and the sweet lemons. 

Citrus aurantifolia. — The limes including both the sour 
Mexican and Rangpur limes and the sweet limes which 
latter are considered to be of hybrid origin. 

THE CITRUS PLANT 

The Root 

Citrus trees differ from many plants in having no root- 
hairs whatever upon the fibrous, feeding roots. The 
feeding roots are comparatively large, very abundant, and 
grow very rapidly. Those sheared off each year by the 
plow in turning under a cover crop are quickly replaced. 
In shallow soils, however, where most of the fibrous roots 
are near the surface, it is unwise to be too reckless with the 
large turning plow. Under arid conditions the feeding 
roots are not confined to the surface layer of soil, but 
where there is no layer of hardpan to interfere they dis- 
tribute themselves throughout the soil usually between the 
eighth and thirty-sixth inch levels. In very deep, well 
aerated soils they may forage much deeper. 

The large main roots serve in a double capacity ; 
as braces to hold the tree upright against the wind, 
and as conveyors of water and food between the fibrous 
feeders and the trunk. Large perpendicular roots known 
as tap-roots are not essential to the health or well-being of 
the trees and are invariably cut when the young nursery 



46 Citrus Fruits 

trees are dug for transplanting. Subsequently the sweet 
orange root will devote itself mainly to sending out laterals, 
while the sour orange will usually send down two or three 
strong tap-roots in the place of the one which was cut. 
The pomelo shows much variation in regard to the 
formation of tap-roots. 

Wood Structure and Growth 

Citrus wood is very closely knit in structure, being 
hard, strong, and tough. It is light in color, with very fine 
grain and with no apparent heart wood ; that is, there is 
no difference in color between heart wood and sap wood. 
The rings observable in a cross section are close together 
and are of no value in determining the age of the citrus 
tree, as they are in the case of pine or oak trees. This is 
on account of the fact that the citrus tree forms several 
rings each year according to the number of vegetative 
growths. The citrus tree does not grow at a uniform rate 
during the season, but makes three or more growths of new 
twigs and leaves each year, with corresponding rest periods. 
The heaviest growth is in the spring just before blooming, 
the flowers being borne on the new shoots. Another 
smaller and more irregular growth is made in mid-summer, 
and a third in the late fall. The number of growths made 
and the times they occur vary with the local weather con- 
ditions and the method of irrigation. 

The main framework branches of old lemon trees often 
present a curious flattened shape next the trunk. The 
greatest diameter is perpendicular, but the width of the 
rings is much thicker on the lower than the upper side, the 



Citrus Botany, Gross Structure, and Habits of Growth 47 



center of growth being crowded close to the bark on the 
upper side. This curious condition is entirely normal in 
the lemon and greatly strengthens the branches, enabling 
them to carry a much larger load without breaking. 

There are two sap currents in the trunk and branches, 
one consisting of dissolved mineral matters taken from the 
soil water by the roots, which 
passes up through vessels in the 
wood to the leaves ; and an- 
other, consisting of elaborated 
plant food, and other complex 
substances, which passes down 
through the inner bark and 
nourishes every growing part, 
even the tips of the longest 
roots. It should be remembered 
that . the action between root 
and leaf is reciprocal. The 
most remote tip of the longest 
root must await the return of 
the elaborated sap from the 
leaves before it is able to grow 
a fraction of an inch. For sake 
of emphasis we repeat : the 
roots of a plant are quite as de- 
pendent upon the leaves for elaborated food as they are 
upon the soil for raw food, for roots cannot use raw mineral 
food. That the downward current of elaborated sap takes 
place through the bark is proved by the swelling which 
occurs just above the point of constriction when a label 
wire is overlooked and allowed to remain, on a young tree. 




Fig. 10. — Growth rings in s 
flattened brace limb of lemon. 



48 



Citrus Fruits 



Advantage is taken 
of this fact in the 
process known as 
"ringing" which is 
chiefly used with 
grapes and pears. A 
ring of bark half an 
inch wide is removed 
from the small branch 
which bears a fruit 
cluster. The fruit 
and leaves continue 
to draw food from 
the roots through the 
wood, but as the 
branch is prevented 
from returning its pro- 
portionate share of 
elaborated food to 
the trunk and roots, it 
soon accumulates an 
extra amount which 
causes the fruit to 
grow to an unusually 
large size. By this 
method a Navel orange 

Fig. 11. -Result of experiment which shows wa f Policed which 
that a girdled orange tree may grow new weighed 3 \ pounds 
L, untreated; and measure d 18 inches 

in circumference. 1 




B, treated. 



1 Scientific American, Dec. 14, 1912, p. 515. 



Citrus Botany, Gross Structure, and Habits of Growth 49 

The line which separates the two currents of sap is 
known as the cambium and is roughly represented by the 
line of cleavage when a strip of bark is pulled away from 
the trunk. It is on this line that growth takes place, the 
cells dividing continually, one part going to build wood 
and the other causing a thickening of the bark. 

Citrus trees are apt to form large quantities of gum along 
the line of the cambium, when stimulated by the growth 
of fungous parasites, or by other causes, the exact nature 
of which are not clearly understood. 

Many trees are unable to grow new bark direct from the 
cambium, but heal over wounds by pushing new tissue 
out from the sides of the wounds. The citrus tree will 
often grow new bark direct from cambium laid bare by 
gophers or gum-disease. Occasionally a tree which has 
been entirely girdled will grow new bark and recover. 
The bark of citrus trees is also peculiar in that it retains 
some green matter or chlorophyll and continues to function 
as a leaf until the tree reaches a great age. 

Leaves 

With the exception of Citrus trifoliata, all citrus trees 
are evergreen ; that is, the bulk of the leaves do not fall 
before the new leaves have expanded. A few of the oldest 
leaves may fall at any time of the year, but the period 
of heaviest fall is in April and May after the spring growth 
has taken place. The normal life of an orange leaf depends 
on the kind of wood upon which it is borne. Leaves on 
the fine fruiting brush usually remain on the tree for about 
fifteen months, while leaves on vigorous upright vegeta- 



50 Citrus Fruits 

tive growths will remain green and in flourishing condi- 
tion for three and even four years. The leaves on the 
trunks of nursery trees, if protected and not removed, will 
usually remain for several years. It is customary to re- 
move these leaves at the time the tree is dug for the purpose 
of reducing transpiration. 

In the case of the trifoliate orange the leaves fall in the 
autumn, the tree remaining bare during winter and until 
after the blooming period in spring. 

Citrus leaves vary in shape and size with the different 
species ; the pomelo and Seville orange having broad wings 
on the petioles, while the sweet orange has a very narrow 
wing and the citron none at all. The width of these wings 
will vary a good deal, being wider on the vigorous shoots 
and very much smaller on the fruiting brush. The edges 
of the sweet orange leaf are entire, while with the lemon and 
lime the edges are indented or crenate. Most, if not all, 
of the stomata or breathing pores are situated on the under 
side of the leaves, and this is a distinct advantage when the 
upper surfaces of the leaves become coated with dust from 
the roads during the dry season, or with cement dust from 
near-by cement mills. 

One striking characteristic of all citrus leaves is the pres- 
ence of numerous glands, which may be easily seen with the 
unaided eye, although they do not project above the sur- 
face of the leaf. These glands are filled with a fragrant 
and aromatic oil which is very volatile and gives to the 
freshly crushed leaves their characteristic odor. This odor 
varies with the different species. One method of distin- 
guishing between sweet and sour stock seedlings in the 
nursery is by recognizing the odor of the crushed leaves. 



Citrus Botany, Gross Structure, and Habits of Growth 51 

Thorns 

Sharp, slender thorns are characteristic of most kinds 
of citrus trees. Seedlings of the sweet orange have per- 
haps the most formidable thorns and these are a serious 
hindrance in harvesting the fruit and pruning the trees. 
The trifoliate orange has short, thick thorns which are very 
numerous. Certain cultivated varieties are practically 
free from thorns, and this quality adds much to their 
popularity. Thorns are borne in the axils of the leaves, 
and their size, in a given variety, depends largely upon the 
vigor of the shoot upon which they occur, being long on 
rapidly growing shoots and short and inconspicuous on 
the fruiting brush. The Navel orange and Eureka lemon 
are practically thornless varieties ; yet on water-sprouts 
long sharp thorns may sometimes appear. 

Thorns are objectionable not only on account of the 
difficulty occasioned in picking fruit, but also on account of 
the injury done to the fruit itself. When the wind tosses 
the branches about, the fruit is stabbed on many sides by 
the thorns, giving an excellent opportunity for inoculation 
and consequent fungous decay. In dry 'weather when 
small wounds are quickly dried (and perhaps, to a certain 
extent, cauterized by the escape of oil from the broken oil- 
cells) there is less decay of fruit on the trees from this 
cause. While this is true, the constant rubbing or pricking 
of a fruit against the point of a thorn will so irritate the 
rind as to cause a very ugly callous to form on the skin 
and thus ruin the market value of the fruit. 

There is a widespread belief among citrus nurserymen 
and others that thorns may be largely eliminated from any 



52 Citrus Fruits 

variety by careful selection of budwood through several 
bud generations. We know of no published data of scien- 
tific experiments to determine this point and doubt very 
much whether the grounds for this belief are sufficient. 
It can do no possible harm to select only thornless bud- 
wood for propagation, and where this happens to result 
in the separation of pure-line mutants which vary in thorni- 
ness much good may be done. On the other hand it is 
difficult to conceive of how progress can be made by selec- 
tion within the pure-line. 

Flowers 

Citrus flowers are large, showy, and fragrant, and are 
borne in great profusion. They are mostly waxy white, 
although in the lemon and citron the backs of the petals 
are tinged with purple. The flowers are mostly perfect 
or complete, consisting of a green calyx with three to five 
lobes, subtending white petals, four to eight in number, 
which are thick, fleshy, and covered with oil glands. The 
stamens are numerous, twenty to sixty in number, their 
filaments (stalks) being more or less united. The style 
and stigma are large and conspicuous. The exudation of 
white mucilage by the stigma is quite copious, as is also 
the watery nectar in the base of the flower cup. The 
pollen is golden yellow and is produced in abundance 
except in certain varieties. The orange has flowers borne 
in cymes on shoots of the current year's growth. In the 
case of the lemon, kumquat, and others, the new growths 
are sometimes so short (the leaves appearing as mere 
bracts), that the flowers have the appearance of being 
borne on old wood. 




Fig. 12. — Valencia orange blossoms. 
53 



54 Citrus Fruits 

The flowers of the orange and pomelo appear during 
April and early May. Occasionally a bunch here and there 
or even an entire tree may bloom at some other season, but 
the fruits from such off-season blooms will usually be ab- 
normal in shape and inferior in quality. Lemons bloom 
and set fruit the year round with the period of most abun- 
dant bloom coinciding with that of the orange. 

Lemon trees are peculiar in that they bear flowers of 
several kinds. Those that produce fruit are perfect, con- 




Fig. 13. — Lemon blossoms showing perfect, partly aborted, and 
aborted pistils. 

taming both stamens and pistils. There are other flowers 
borne by the same tree in which the pistils are reduced to a 
mere rudiment while the stamens are large and well de- 
veloped. In addition to these there are certain abortive 
buds, observed on the Eureka lemon chiefly, in which the 
petals do not develop but remain closed, the stigma forcing 
its way out between them. Only the perfect lemon blos- 
soms set fruit, although the second kind mentioned may 
aid in pollination. Lemons require about nine months 
from blossom to maturity of fruit. A few fruits will come 



Citrus Botany, Gross Structure, and Habits of Growth 55 

up to size in six months, while some will remain undersized 
for a year and finally turn yellow, at which time they are 
picked regardless of size. 

Pollination 

The larger number of fruits, such as apples, plums, 
grapes, and strawberries, require pollination in order to set 
fruit. Some kinds of citrus fruits require pollination in 
order to set and mature fruit, but a large number do not. 
Many forms of citrus bear parthenocarpic or seedless 
fruits, and with these pollination is not only unneces- 
sary, but is apparently a disadvantage, inasmuch as it 
results in some cases in the formation of seeds which 
are objectionable. 

In Florida a large number of varieties are grown com- 
mercially, and as most of them contain seeds it is probable 
that a large proportion at least require pollination for their 
best development. Florida writers are strangely silent on 
this point. In the citrus districts of the Southwest it hap- 
pens that the five varieties chiefly grown — Washington 
Navel and Valencia oranges, Eureka and Lisbon lemons, 
and Marsh pomelo — are more or less parthenocarpic. 
Those kinds which contain some seeds, as the Lisbon lemon 
for instance, are able to set and mature fruit without polli- 
nation, which results merely in the formation of seeds. 1 
The Washington Navel orange flowers contain no pollen 
whatever and in the Eureka lemon viable pollen is rare 
except at certain seasons, yet these varieties produce quite 

1 Unpublished Report on Pollination Experiments by the 
Writer. 



56 Citrus Fruits 

as well when planted in solid blocks of hundreds of acres 
far from other varieties, as they do in mixed plantings. 

T. Ikeda x in a series of brilliant experiments has shed 
much light on this interesting subject. His principal 
results may be summarized as follows : 

1. Certain varieties of oranges require pollination in 
order to set fruit. 

2. Certain varieties of oranges which ordinarily contain 
seeds will without pollination set and mature a small num- 
ber of parthenocarpic fruits. 

3. Many varieties of oranges are uncongenial, cross- 
pollination being followed by dropping of flowers and 
young fruit. 

4. Cross-pollination between seed bearing and parthe- 
nocarpic varieties may result in the setting and maturing 
of fruit containing viable seeds, provided the pollen used 
is that of a congenial variety. 

5. Parthenocarpic varieties do not require the stimulus 
of pollination in order to set and mature fruit. 

6. The pollen-tube may reach the ovule as soon as 30 
hours after pollination. Fusion of male and female cells 
may begin 48 hours after pollination. Fertilization is 
completed in from 48 to 72 hours after pollination. 

7. In the Washington Navel and Satsuma oranges the 
embryo-sacs usually disintegrate instead of developing 
into embryos capable of being fertilized. 

Occasionally a few normal embryo-sacs are produced 
in both Washington Navel and Satsuma oranges. 2 Thus 

1 Tomoehika Ikeda, " On the Parthenocarpy of Citrus Fruits," 
Jour. Sci. Agr. Soc. Tokyo, Vol. 63, 1904. 

2 The factors which influence the frequency of occurrence of 



Citrus Botany, Gross Structure, and Habits of Growth 57 

a few seeds may be produced provided the particular fruits 
having the normal embryo-sacs happen to be pollinated 
with viable pollen from congenial varieties. It is the 
remoteness of the chance of this occurring under ordinary 
field conditions that accounts for the comparative seedless- 
ness of these fruits. Apparently there is nothing in the 




Fig. 14. — Orange flower X 2. p, pistil; a, stigma; c, style; o, ovary; 
s, stamen; b, anther; e, filament; d, nectary; g, sepal; /, petal. 



structure of the blossoms of either the Washington Navel 
or the Satsuma orange which would interfere in any way 

normal embryo-sacs have not been fully worked out. Experi- 
ments now being carried on by the writer seem to indicate that 
the climate factor is most important. Normal embryo-sacs of 
Washington Navels occur much more frequently at Riverside 
than at Whittier where they are very rare. For this reason plant- 
breeders wishing to use the Navel as a maternal parent in cross- 
breeding work may expect greater results from crosses made at 
Riverside or other interior points. 



58 Citrus Fruits 

with the germination of pollen or normal extension of the 
pollen tube. 

The occasional seeds sometimes found in Washington 
Navel oranges as they occur on the market are undoubt- 
edly due to cross-pollination with some other variety by 
insects or other agencies. The question as to what would 
be the result should these seeds be planted and reared to 
maturity has already been answered by the experiment 
of W. H. Backus of Riverside, a part of whose report is 
here quoted. 1 

"Some years ago when almost every one was budding 
over their seedlings to Navels, I thought the result might 
be too many early oranges. At that time I did not think 
the Valencia the most desirable late orange, as a Cali- 
fornia orange should have high color in addition to being 
late. 

"To obtain this desirable feature, together with high 
color quality and medium size, I tried hybridizing the 
Mediterranean Sweet on the Washington Navel, three 
successive seasons, cutting all the oranges when ripe for 
seed. Altogether I secured about fourteen hundred seeds 
that were well matured. 

"These were planted in the seed bed, but owing to my 
lack of experience in nursery work, a large percentage of 
the little trees, of the first and second plantings, died when 
about three inches high. One peculiar thing to me was 
that over 90 per cent of the seeds sprouted from two to six 
shoots each. 2 

"The young nursery stock was much neglected for three 

1 Riverside Daily Press, March 2, 1909. 

2 An interesting record of polyembryony. 



Citrus Botany, Gross Structure, and Habits of Growth 59 

or four years, when I took buds from the most thrifty to 
bud over old trees. Although these buds stand 16 to IS 
feet apart in an old grove, still they made a rapid growth, 
equal to a straight seedling, and are now about 25 feet 
high. 

"The disappointment came when they began to bear. 
Many were of no value at all ; the best were early, some 
apparently earlier in ripening than the Navel, but generally 
of good color, sweet and seedless. The trees were exceed- 
ingly thorny and some much more thrifty than others ; 
many appeared to be good bearers while others were shy 
or very late in coming into bearing. Consequently al- 
most all have been rebudded or dug up." 

Polyembryony 

A peculiar thing about citrus seeds is the fact that a 
variable proportion of them will give rise to from one to 
ten distinct seedlings each. This is known as polyem- 
bryony and is due to a number of adventitious embryos 
appearing in the embryo-sac. Some of these bud embryos 
may develop into seedling plants along with the sexual 
embryo which requires fertilization in order to develop. 
This explains why seedlings in the seed bed often appear to 
grow in bunches even though the seeds were planted sepa- 
rately. As only one of the seedlings arising from any 
given seed is the result of pollination and fertilization, it 
follows that the others must be vegetative seedlings, and, 
in case the seed is from a known variety, will reproduce 
the variety true from seed without the necessity of bud- 
ding. It is impossible, however, to distinguish the sexual 



60 



Citrus Fruits 



seedling from the others in 
the early years of growth, 
except in the case of crosses 
between forms which have 
very differently shaped 
leaves. It would be imprac- 
ticable to propagate Navels 
true from seed on account 
of the rarity of seeds and the 
necessity of pollinating the 
flowers, but it would be a 
simple matter with seedy 
varieties were it not for the 
difficulty above mentioned. 

Structure of the Fruit 

According to Bonavia, 1 
the citrus fruit consists mor- 
phologically of two whorls 
of transformed leaves, one 
going to make the rind and 
the other to make the group of carpels or sections of 
the fruit. Each carpel is supposed to be a leaf folded 
over in such a way that its two edges meet in the 
center on the axis of the fruit and along which the 
seeds are borne. The number of these sections or 
divisions varies considerably even in the same variety. 
The little juice sacks or vesicles within each carpel are 
supposed to be transformed oil glands of the leaves. As 
1 E. Bonavia, "Oranges and Lemons of India," Vol. I. 




Fig. 15. — Polyembryony. Two 
orange seedlings from one seed. 



Citrus Botany, Gross Structure, and Habits of Growth 01 

varieties of double flowers are formed by the growth of an 
additional whorl of petals, so varieties of double fruits 
may come about by the growth of additional whorls of 
carpels, and this is what has taken place in the case of the 
Navel orange, as any one may observe by making a num- 
ber of thin transverse sections through the apical end of a 
Navel orange, and studying these sections. The vesicles 
in citrus fruits are multicellular and are attached by a 
stalk in nearly all cases to the outer wall of the carpel, 
only a very few being attached to the sides. These vesi- 
cles are fed directly by fibro-vascular bundles branching 
from the stem and running through the white spongy 
tissue which composes the inner part of the rind. The 
seeds vary in number from none as in the Navel to fifty 
or more in the trifoliata. They are attached to the inner 
edges of the carpels. 

Citrus fruits in common with other fruits are not to be 
considered as so much dead matter after they are plucked 
from the tree. They live and breathe (transpire) for many 
months. They also lose water and shrink in size and 
weight as a result of giving off carbon dioxide and water 
vapor. If protected from infection by decay-producing 
organisms, oranges or lemons will keep one year or more, 
when kept moist and cool, but will eventually die and 
collapse from enzymatic fermentation. If they are al- 
lowed to lose moisture, they will dry up into balls as hard 
as wood. An understanding of the vital processes going 
on in citrus fruits is highly important in connection with 
the curing of lemons and pomelos. (See Chapter XVI.) 

Chemistry of the Fruit. — Citrus fruits from the same tree 
may vary much in their composition. Commercial Cali- 



62 



Citrus Fruits 



Analyses of California Oranges and Lemons 
(From Bull. No. 93, Univ. Cal. Agr. Exp. Station) 



A. Proximate Analyses 


Wash. 


Med. 


Paper 


Malta 


Eureka 


Name of Variety 


Navel 


Sweet 


Rind 


Blood 


Lemon 


Average weight in grams 


300 


202 


138 


177 


104 


Water, per cent . 


85.82 


85.19 


84.76 


85.68 


83.82 


Organic matter, per cent 


13.95 


14.32 


14.77 


14.39 


15.61 


Ash, per cent .... 


.42 


.47 


.46 


.42 


.56 


Rind, per cent 


28.4 


27.0 


19.2 


31.0 


32.0 


Pulp less juice, per cent 


27.7 


24.0 


25.9 


24.0 


24.5 


Seeds, per cent . 




0.8 


1.6 




0.12 


Number of cc. of juice, 














107 


86 


65.4 


71 


38 


Solid contents of juice 












by spindle .... 


12.80 


12.60 


12.10 


13.55 


11.90 


Total sugars in juice (by 












copper inversion), per 














9.92 


9.70 


8.71 


10.30 


2.08 


Cane sugar in juice (by 












polariscope), per cent 


4.80 


4.35 


3.48 


5.85 


0.57 


Citric acid, per cent 


1.02 


1.38 


1.35 


1.61 


7.66 


Nitrogen in fresh fruit, 












per cent .... 


0.211 


0.154 


0.228 


0.168 


0.151 


Albuminoids in fresh 












fruit, equivalent to 












nitrogen, per cent 


1.31 


0.96 


1.43 


1.05 


0.94 



B. Analyses op Ash 



Oranges 



Lemons 



Potash (K 2 0), per cent 

Soda (Na 2 0) 

Lime (CaO) 

Magnesia (MgO) 

Peroxide of iron (Fe 2 3 and alumina 

(A1 2 8 ) 

Br. oxide manganese (Mg 3 4 ) . 

Phosphoric acid (P 2 5 ) 

Sulphuric acid (S0 3 ) 

Silica (Si0 2 ) 

Chlorine (CI) 



48.26 
1.76 

29.87 
4.40 




Citrus Botany, Gross Structure, and Habits of Growth 63 

fornia oranges contain about 30 per cent rind and 40 per 
cent juice when freshly picked from the trees. The percent- 
age of juice increases as the fruit is cured for the water in 
the rind is lost first by evaporation and transpiration. 
California Navel oranges will analyze about 10 per cent 
total sugars, 4^ per cent of which is cane sugar, the re- 
mainder being a mixture of other fruit sugars. Navel 
oranges contain about 1 per cent of citric acid. Lemons 
contain about 2 per cent total sugars, of which | per 
cent is cane sugar, and 1\ per cent of citric acid. 

Harvest Season 

In California, oranges and lemons are harvested through- 
out the year. The orange season begins with Navels about 
November 15 in central California and moves south- 
ward. The last Navels are shipped from southern districts 
about May 1. During May and a part of June miscel- 
laneous varieties including seedlings and some late Navels 
are gathered and shipped. The Valencia harvest begins 
in central California in June and continues southward, 
the last of the crop going forward from the coast districts 
in November and thus overlapping the Navel crop of the 
next season. 

Lemon trees are picked over once each month or about 
ten times a year, the trees bearing fruit in all stages of 
growth from the blossom to the mature fruit at all times. 
Lemons should not be allowed to ripen on the tree . They 
should be picked when they have reached a diameter of 
2^- inches in summer and 2jq inches in winter and 
spring, regardless of color. 



64 Citrus Fruits 

Longevity 

Citrus trees are naturally long lived. If planted on 
deep, rich soil and given good care, they should bear profit- 
ably for fifty years or more. Much has been said in print 
about a natural limit of profitableness in the case of the 
Navel orange. This limit is sometimes placed at twenty- 
five years. The writer believes this to be a mistake. 
Navel oranges as well as other kinds of citrus will live 
and produce generous crops to a very great age, provided 
they are growing on deep, fertile soil and are well cared 
for. 



CHAPTER IV 
VARIETIES 

As stated in a previous chapter, the first oranges grown 
in California were seedling sweet oranges. Unlike the 
apple and peach, the sweet orange will come fairly true 
from seed, the fruit from practically all seedlings being 
marketable. Each tree, however, varies from its neigh- 
bors in many minor characters, such as size, productive- 
ness, season of ripening, seed content, flavor, and shipping 
qualities. The fruit from an orchard of seedlings lacks 
uniformity, which is one of the chief requisites of a com- 
mercial fruit product. Seedling trees grow very large, 
so large in fact that it is expensive to gather the fruit and 
often difficult or impracticable to inclose the trees in fumi- 
gating tents. For these and other reasons the old seedling 
orchards have been gradually cut down and replaced by 
budded trees or top-worked to improved varieties, until 
at the present time comparatively few remain. 

During the transition from seedling to budded orchards 
the question as to which of the many varieties available 
would prove the most profitable was a favorite subject for 
discussion. 

By 1885, enterprising nurserymen had introduced most 
of the important varieties of the world, and these were 
f 65 



66 Citrus Fruits 

tested alongside many local seedlings of special merit. 
Probably as many as one hundred different varieties were 
given trial. At the early citrus fairs such imported vari- 
eties as the Du Roi and Pernambuco were to be seen exhib- 
ited side by side with California productions such as 
Asher's Best and Bostram's Prize. The elimination of the 
less profitable varieties took place rather rapidly, and by 
the year 1900 we find the Washington Navel orange oc- 
cupying more land than all other varieties of oranges com- 
bined. At this time the two fittest survivors, the Navel 
and Valencia, dominated the field. 

DESCRIPTIONS OF VARIETIES OF ORANGES 

Washington Navel (Bahia, Riverside Navel). — Form 
rounded, slightly tapering at apex, somewhat longer than 
wide ; small umbilicus ; size variable, 2\ to 3| inches in di- 
ameter ; color orange when grown near coast, deep orange 
when grown in interior valleys ; juice abundant, orange 
colored ; flavor excellent, acid and sugar well blended ; 
vesicles large, spindle shaped ; skin \ to \ inch thick, varying 
from smooth to pebbly ; size of secondary orange under 
umbilicus variable, often f inch in diameter. Seeds none, 
except in very rare cases. 

Tree semi-dwarf, vigorous, very precocious, prolific, 
thornless or with thorns only on vigorous shoots ; appearance 
of blossoms normal except for the fact that the anthers are 
cream colored and contain no pollen whatever. Introduced 
from Bahia, Brazil, 1870, by the late William Saunders, then 
in charge of U. S. Government propagating grounds at 
Washington, T). C. 

The Washington Navel well deserves the title "King of 
Oranges." Under the climatic conditions of California and 



Varieties 



67 



Arizona this variety approaches very nearly to the ideal 
orange. The dry air, bright sun, and cool nights, operating 
in conjunction with the skill of the grower and packer upon 
the natural qualities and character of this orange, have made 
it the greatest commercial orange in the world. These 




Fig. 16. 



•The earliest known illustration of a Navel orange. 
Ferrarius' " Hesperides," 1646. 



From 



thornless trees combine heavy and regular yields with a 
high color of the fruit, a silkiness of texture, and a general 
finish which is almost perfect. It is solid and full of juice 
of exceptionally high flavor, but it is entirely lacking in 
seeds. It is a very good keeper and travels well to the most 
distinct markets. It possesses moreover a natural trade- 



68 Citrus Fruits 

mark, in the shape of a navel-like mark, which is beyond 
imitation and which is of great market value. More than 
eight million boxes of Washington Navels are now being 
grown and shipped out of California annually, and the prices 
received are encouraging a rapid increase in acreage. 

In California, the Washington Navel reaches its highest 
development in quality on the gravelly soils of the foothills 
in the warmer interior valleys. The yield, however, is not as 
heavy as it is near the coast, where the fruit tends to ripen 
later. On the deep heavy soils of the coast country, the 
skin tends to be somewhat thicker with a rougher surface 
and paler color. 

One characteristic of the Washington Navel is its tendency 
to sport or throw out occasional branches bearing fruit of a 
different type. By far the larger number of these sports 
are retrogressions, and careless cutting of bud-wood for prop- 
agating purposes from trees containing such sports has re- 
sulted in a great lack of uniformity in existing orchards. 
Occasionally sports are found which possess some character 
of supposed value, and by the propagation of these new 
varieties have appeared. Among such offspring we note 
the following : Thomson, Buckeye, Navelencia, Nugget, and 
Australian. 

Thomson. — Fruit of medium size ; skin thin and very 
smooth in texture ; ripens early. The quality of the Thom- 
son is somewhat inferior to the Washington Navel, but it 
has a superior appearance. For certain markets in some large 
cities where appearance rather than quality determines 
demand, it commands a premium of from twenty-five to 
fifty cents a box over the Washington Navel. For this 
reason, it is being grown on an increasing commercial scale. 

The Thomson was introduced by A. C. Thomson of Duarte, 
Los Angeles County, about 1891, and is generally thought 



Varieties 



69 



to be a bud sport from the Washington Navel. Consider- 
ing the story told by Mr. Thomson of his method of pro- 
ducing this form, it is possible that it may be a periclinal 
chimera ! 

Buckeye. — Fruit medium in size with peculiar bands or 
ridges of deeper orange color ; skin smooth and of fine 
texture ; ripens early. Introduced by R. M. Teague at 
San Dimas, California. 

Navelencia. — Fruit medium to large, smooth and thin- 
skinned ; season said to be somewhat later than Washington 
Navel ; more susceptible to frost than Washington Navel. 
Originated by A. C. Thomson, at Duarte, California. 

Nugget. — Fruit oblong, medium in size, smooth, solid, and 
thick skinned, often with an objectionable but characteristic 
crack or slit in the skin on one side ; young twigs slender 
and willowy, tree umbrageous with very brittle wood. 
Originated by J. P. Englehardt at Glendora. Introduced 
by R. M. Teague at San Dimas, California. 

Australia7i. — Fruit very variable, rough, coarse ; navel 
often closed ; skin thick, especially near stem end. Tree 




Fig. 17. — One type of Australian Navel orange. 



70 Citrus Fruits 

large with upright, open growth, shy bearer. Strictly 
speaking, there is no such thing as the Australian Navel. 
The term is a misnomer in the same sense as the term English 
walnut is when applied to the Persian walnut. In common 
usage, however, the name applies to a certain rough-fruited 
and shy-bearing sport of the Bahia Navel, which was un- 
wittingly introduced into California from Australia in an 
effort to secure the true Bahia. Some persons go further 
and call any undesirable sport an Australian, thus using the 
term as an adjective rather than as a noun. Some other 
persons apply the term Australian to the rank growing 
wood resulting from water sprouts in the tops of the trees, 
which tend to produce coarse, rough fruit. This latter is 
clearly an improper use of the term. 

Valencia. — Form oblong, somewhat flattened with de- 
pressed ring at apex, tapering toward base ; size medium, 
color pale orange deepening with maturity ; skin smooth or 
slightly pebbled, thin but tough ; juice plentiful, flavor sub- 
acid ; seeds variable, sometimes three to six, often none ; 
season late, from June to November. Tree large, vigorous 
grower, prolific, thorns few and small. 

The Valencia hangs on the tree well during the summer but 
in interior valleys it is apt to turn green again in late summer. 
When grown in such situations, it should be harvested in 
May and June. In deep heavy soils near the coast, it can 
safely be held till November or December. 

This famous orange originated in the Azores. Thomas 
Rivers, the English nurseryman, imported it, with other 
varieties, from the Azores into English glass-houses and first 
catalogued it in 1865 under the name "Excelsior." S. B. 
Parsons, a Long Island nurseryman, bought trees from Rivers 
and brought them to America about 1870. He kept them in 
his greenhouse for several years and then moved them to 



Varieties 71 

his nursery near Palatka, Florida. Parsons sold some of 
these trees to E. H. Hart, of Federal Point, Florida, who 
gave the variety the name "Hart's Late" or "Hart's Tar- 
diff." Fruit was first exhibited before the Florida Fruit 
Growers' Association on April 25th, 1877. 

A. B. Chapman, of San Gabriel, California, imported a 
number of varieties of citrus from Thomas Rivers about 1870- 
72. One variety labeled Navel, turned out not to be a Navel, 
but of distinct value on account of its ripening very late in 
the season after other varieties were off the market. Finally, 
at the suggestion of a Spanish laborer, Mr. Chapman called 
the orange " Valencia Late " and many trees were propa- 
gated and sold under this name. 

California nurserymen early secured stocks of Hart's 
Tardiff from Florida, and many thousands of trees were 
planted. When it became evident that these- were the 
same as the Valencia, the latter name was adopted and 
is now used exclusively in California. This name has 
become so well fixed in the trade and market reports as well 
as in the every-day speech of the people that it is idle to 
attempt to change the name in order to conform to the rules 
of horticultural nomenclature. 

The fame and popularity of the Valencia orange has been 
greatly advanced in California by the wonderful record made 
by a superb orchard of this variety owned by C. C. Chapman 
at Fullerton in Orange County. 

Mediterranean Sweet. — Form round or somewhat flattened ; 
size medium to small ; color deep orange ; skin of fine texture ; 
juice abundant, very sweet ; seeds few, small ; season April 
to May ; tree semi-dwarf with small narrow leaves very 
thickly set, almost thornless. 

Introduced and renamed by T. A. Garey of Los Angeles 
about 1870. Secured from Thomas Rivers of England. 



72 Citrus Fruits 

Paper Rind (Paper Rind St. Michael). — Form round; 
size small, solid with high specific gravity ; color yellow, or 
pale orange ; skin very thin and very smooth ; juice abun- 
dant, colored, with rich vinous flavor ; seeds three to six in 
number, medium sized ; season March to May ; tree semi- 
dwarf, medium thorny, very productive. Introduced from 
the island of St. Michael. 

Ruby (Blood). — Form round or slightly oblong, sometimes 
navel marked ; size medium ; color deep orange or reddish 
when fully mature ; skin smooth ; juice deep orange in color 
changing to red as fruit matures ; flavor very rich and vinous ; 
seeds many ; season March and April, tree of medium size, 
compact growth, almost thornless. Imported from Mediter- 
ranean districts. 

Jaffa. — Form round ; size medium ; color deep orange ; 
skin smooth or slightly pebbled ; juice abundant and of 
excellent quality ; seeds many, large ; season March to May ; 
tree medium sized, more resistant to cold than most other 
sweet oranges, almost thornless. Imported from Palestine, 
where it is largely grown. 

Joppa. — Form oblong, slightly shouldered ; skin thin, 
somewhat pebbled ; juice abundant, sweet, and of fine flavor ; 
seeds few or none ; season March to July ; tree large, thorn- 
less. Originated in 1877 by A. B. Chapman of San Gabriel, 
California, from seed secured from Joppa, Palestine. 

Crafton (Crafton Late). — A late seedling, originated by 
Myron H. Crafts, several large budded orchards of which 
are still in bearing in the vicinity of Crafton, California. It 
is marketed during May and often brings very good prices. 

LEMONS 

In the early days of the industry a large number of Euro- 
pean varieties were tested, but few were found suitable to 



Varieties 73 

the California conditions. Many seedlings were raised also, 
most of which proved disappointing in some important 
respect. At present new plantings are limited chiefly to two 
varieties, the Eureka and the Lisbon. While a few old 
orchards of Villafrancas are still maintained, but few are 
being planted. The Eureka is rapidly gaining in popularity 




Fig. 18. — Eureka lemon, uncured. 

over the Lisbon and it appears that this will soon be the 
only variety planted on a large scale. 

Eureka. — Form oblong, apex nippled, base tapering ; size 
medium ; rind smooth, glossy, sweet ; juice abundant, 
clear, strongly acid, flavor good ; seeds few, often none. 



74 Citrus Fruits 

J. H. Needham, in an essay before the Pomological Society 
at Covina in 1898, says : "The advantages of the Eureka are 
its comparative freedom from thorns, its tendency to early 
bearing, and when properly trained to enormous crops when 
it comes into full bearing, and its continuous blooming and 
setting of lemons all the year, especially in sections com- 
paratively free from frost. The objections are its tendency 
to set its fruit on the tips of the branches, and the inclination 
to grow long canes with but few laterals and to drop its leaves 
on the long canes or branches, thus leaving the limbs and 
fruit too much exposed to the hot rays of the sun in the heated 
term of summer." 

The Eureka lemon originated from a seed planted about 
1870 by C. R. Workman in Los Angeles. Workman and Pres- 
ton began to propagate it, but later sold all the stock to Thomas 
A. Garey, of Los Angeles, who propagated it extensively and 
sold it under the name Eureka. 

Lisbon. — Form oblong or obovate, apex oblique, nippled 
with a characteristic crease to one side of the nipple, base 
tapering sharply to calyx, which is large ; rind thin, smooth, 
sweet ; juice abundant, clear, and strongly flavored ; seeds 
few, sometimes none ; tree large, a strong, vigorous grower, 
foliage thickly set, not precocious, very thorny. 

The Lisbon bears its fruit uniformly throughout the 
tree. The heavy foliage protects the fruit from sunburn. 
The tendency is to bear one large crop maturing in winter, 
with a small amount of summer fruit. Introduced from 
Europe. 

Villafranca. — " Form oblong, slightly pointed at the 
blossom end, rind thin, without, any trace of bitterness ;' 
acid strong, juicy ; nearly seedless. Tree almost thornlessy 
branches spreading and somewhat drooping, foliage very 
abundant, which protects the fruit from sunburn. The 



Varieties 



75 



tree is a strong grower and is considered less susceptible to 
cold than most varieties. Introduced from Europe. 

"The advantages claimed for the Villafranca are that it 
makes a more compact tree and bears its fruit more uni- 
formly over the entire tree, but it requires at least one year 
longer to come into bearing, and the fruits on young trees 




Fig. 19. — Lisbon lemon, uncured. 

are shorter when they have the requisite diameter for picking 
than either the Eureka or the Lisbon." * 

Other varieties still to be found in old orchards and collec- 
tions are Bonnie Brae, Genoa, Sicily, Messina, and Milan. 



POMELOS 

Marsh. — Form flat or obovate ; size small to medium ; 
color light yellow ; rind smooth, variable in thickness ; juice 
1 Lelong, "Culture of the Citrus in California," p. 167. 



76 



Citrus Fruits 




Fig. 20. — Seedless pomelo, flowers and fruit. From Volckamer's 
" Hesperides," 1708. 

abundant ; flavor fair ; pith large, open ; seeds none or one 
to six ; season March to July or later ; hangs on trees well 
all summer. 

According to Hume, 1 this variety was introduced by C. M. 

1 " Citrus Fruits and Their Culture," p. 120. 



Varieties 77 

Marsh of Lakeland, Florida, about 1895 or 1896. The original 
tree was a seedling growing in Lakeland, and was at the 
time of the freeze fully sixty years old. 

The Marsh is the chief variety of pomelo grown commer- 
cially in California and Arizona, although the following may 
be occasionally met with and are doubtless deserving of a 
wider planting. While seedlessness is a very desirable 
character in a fruit, it should not be allowed to outweigh such 
characters as flavor, juiciness, and quality. California is in 
need of a variety of pomelo better suited to the conditions 
than any now available. 

Nectar (Duarte Seedling). — A seedling tree brought from 
Florida and fruited at Duarte, California. The fruit is 
round and solid with smooth skin of pale yellow color. The 
seeds are few and the flavor excellent. 

Duncan. — A flat fruit with rather thick skin and flesh 
of grayish green color, seeds few, season late, quality good. 
Introduced from Florida. 

Triumph. — A fine-appearing fruit and full of juice as 
well as seeds, of which there are many. Somewhat lacking 
in flavor. 

Imperial. — Size medium to large, rind very smooth, 
medium thin, and of fine texture ; little rag ; juice abundant 
and of fine aromatic flavor. R. M. Teague says of this 
variety : " It is one of the best keepers and shippers. The 
tree is a strong upright grower and a heavy cropper." 

Colton {Colton Terrace). — A seedling grown at Colton, 
California. Size medium to large, heavy, subacid, and deli- 
cately bitter ; seeds many ; skin smooth ; oil cells very small ; 
light lemon color, turns slightly orange color when mature. 

Pink-fleshed. — A prolific variety imported from Cuba. 
Flesh deep pink, coarse, and of poor quality. Seeds many ; 
tree very large and ornamental. 



78 



Citrus Fruits 



MANDARINS 

The Mandarin oranges grown commercially in California 
are practically all of one variety, the Dancy, commonly 
known as the tangerine. On account of the confusion in 
name, it may be well to emphasize the fact that "tan- 
gerine" is the trade name for one variety of Mandarin 
orange, the proper name for which is Dancy. The Satsuma 




Fig. 21. — Dancy Mandarin orange. 



is not grown commercially in California and is represented 
only by occasional specimens in gardens and nursery collec- 
tions. Such collections often contain specimens of King, 
Beauty, Mikado, Oneco, and a few others. 

Dancy. — Form oblate ; size medium ; color very deep 
orange red ; glossy ; rind smooth, except about stem end, 
which is nippled, apex depressed ; segments separating 
readily; juice abundant, colored; flavor rich and sprightly; 
seeds five to ten or more, small ; season January to February. 
Tree of upright growth, fruit borne largely on the extremities 



Varieties 79 

of the branches ; somewhat thorny. Parent tree raised from 
seed by Col. George L. Dancy at Buena Vista, Florida. In- 
troduced into cultivation about 1872. 

Satsuma (Unshiu). — Size small to medium, 2 to 3 inches 
in diameter ; shape flat, a little pointed next the stem ; 
color bright orange ; skin rough, wrinkled next the stem, 
very loose and easily separated from the flesh ; core, almost 
none, represented by a cavity often three-eighths inch in di- 
ameter in center ; seeds none ; flesh orange color, darker than 
the skin, not so juicy as some ; flavor very sweet, rich, 
very aromatic, peculiar ; quality very good ; season early. 

This variety is thornless and a dwarf grower. It will 
endure more cold than any other variety of edible citrus 
fruit except perhaps some of the hybrids mentioned below. 
Should be worked on Citrus trifoliata stock or sourstock. 
Introduced from Japan about 1876. 



MISCELLANEOUS VARIETIES 

Swingle-Webber Hybrids. — In 1892, W. T. Swingle and 
H. J. Webber of the U. S. Department of Agriculture under- 
took to produce new and improved varieties of citrus fruits 
by hybridization on an extensive scale. Several new types 
have been produced, examples of which are Citranges and 
Tangelos. The citranges are crosses between the common 
sweet orange and the trifoliate orange. The Rusk, Willits, 
Norton, Colman, Savage, and Rustic have been described. 
The fruits of these hybrids are intermediate in character 
between their parents. They are not nearly so good as sweet 
oranges, but they may be used for making soft drinks, pies, 
and marmalades. Their special advantage lies in their re- 
sistance to cold, which enables them to grow a hundred miles 
or more beyond the northern limit of the sweet oranges. 



80 



Citrus Fruits 



In California they are as yet grown only as specimens for 
exhibition purposes. 

The Thornton is a loose skinned tangelo which resulted 
from crossing the pomelo and tangerine. The juice is sweet, 
lacking the bitter of the pomelo. The Sampson tangelo is 
the result of crossing the pomelo with pollen of Dancy. 
The skin is loose like the tangerine, but the flavor 
includes some of the bitter of the pomelo. The Weshart and 
Trimble are crosses between the Dancy and Parson Brown. 




Fig. 22. — Satsuma Mandarin orange. 



The fruits are larger than the Dancy, which they resemble 
otherwise. 

Several thousand hybrid seedlings of several generations 
are now being grown by the Department of Agriculture 
and additional varieties of merit may come to light in the 
future. 

Citron. — Citron is not grown commercially to any 
extent in California, although good specimens of the plant 
may be found in many parts of the state and there is at least 
one good-sized orchard. The tree is small in stature with a 



Varieties 81 

shrub-like growth. It is more tender to frost than the 
orange, but less tender than the lime. As early as 1880, 
experiments showed that California-grown citron, when 
properly processed or candied, was equal in every respect 
to the imported article. The consumption of candied 
citron in the United States is very small compared with 
that of oranges and lemons, and this probably is the main 
reason why so little interest has been taken in it. There 
appears to be no good reason why California should not 
produce all the candied citron consumed in this country. 
Most of the varieties of Europe have been introduced for 
trial. The Corsica appears to be one of the best. 

Shaddock. — The shaddocks are of no commercial im- 
portance. Occasional trees may be found in collections and 
in yards and gardens throughout the citrus belt. They 
appear to vary in resistance to cold, some being as hardy 
as the orange. The fruit is very large, round, oblate or pear 
shaped ; skin very thick, sometimes two inches thick ; seeds 
many or none ; flesh pale yellow or reddish, juice acid and 
often very bitter ; in some forms the young growth is pubes- 
cent. Trees ornamental, but not more so than the pomelo, 
which is both useful and ornamental. 

Lime. — Three kinds of limes are grown for home use to a 
limited extent in California. The Sour or West India lime, 
together with the Rangpur, are used for cooling drinks 
while the Sweet lime is eaten out of the hand like the 
orange. Limes have never been grown commercially in 
California. All but the Rangpur are very tender to frost, 
even much more so than the lemon. The Rangpur is said 
to be fully as hardy as the lemon. In the early days a sour 
form of Mexican lime was much planted as a hedge plant 
around orange orchards. They proved too tender for most 
localities and were difficult to fumigate and keep free from 




Fig. 23. — Nagami kumquat. 



(82) 



Varieties 83 

scale insects. For these reasons they have mostly dis- 
appeared. 

Kumquat. — In California the kumquats are used chiefly 
as ornamentals, although a few find their way into 
the markets and an occasional small shipment is sent out of 
the state. They are especially suited to pot culture, when 
budded on Citrus trifoliata root, and are convenient to move 
about as desired on verandas and in formal gardens. The 
fruit is small, about one inch in diameter, with sweet aromatic 
rind. The fruit may be eaten fresh or made into delicious 
preserves. The Marumi kumquat is most hardy to cold. 
It has round fruit, borne in great abundance, ripening in 
October. Twigs somewhat thorny. The Nagami kumquat 
is oblong, slightly pear shaped ; fruit golden yellow ; rind 
smooth, aromatic, and spicy. Tree thornless, slightly more 
tender to frost than Marumi. 

Sweet lemon. — This form of citrus is met with only in 
collections, as there is no market demand for a sweet lemon. 
It is a question whether this should be grouped with the 
lemons or with the oranges. The fruit is like a lemon in 
shape but the flowers are white like those of the orange. 

The Trifoliata. — ■ In the early days this species was grown 
to a considerable extent in California as a hedge plant. 
These hedges have been largely done away with, and as the 
plant is not needed as an ornament, it is rapidly becoming 
rare in the state. 



CHAPTER V 
THE CITRUS NURSERY 

The day of the seedling orange grove is past in Cali- 
fornia. Now all trees for new plantings are budded 
as a matter of course. Many of the large planters prefer, 
and find it highly profitable to grow their own trees. Yet 
the business of raising citrus trees for sale has reached 
large proportions. Citrus nursery stock not only fills 
the home demand, but is shipped in large quantities to 
many foreign countries. 

THE SEED-BED 

The first step in the production of a citrus tree is the 
raising of the root or stock upon which the desired variety is 
to be budded. The comparative value of all the different 
stocks will be discussed in Chapter X. We will simply 
say here that at present the demand is about as follows : 
sour-stock, 85 per cent ; sweet-stock, 9 per cent ; pomelo, 
5 per cent; and all others, 1 per cent. Sour-stock seed 
comes from the wild thickets of Florida and Cuba, and is 
sold in California for from $30 to $50 a bushel. Between 
five and six hundred bushels of sour orange seed was 
planted in California in the year ending June 30, 1913. 

84 



The Citrus Nursery 



85 




Fig. 24. — Citrus seed-bed under lath. 



86 Citrus Fruits 

This seed may be secured in the fall and kept in a cool, 
dark cellar. It should not become excessively dry. Sour 
seed runs about 30,000 seeds to the bushel, half of which 
should come up and produce trees. 

Sweet orange seed is secured from the various seedling 
orchards in California. It will not endure drying, but 
must be handled quickly and kept moist. The seed 
stores do not keep sweet seed on hand in quantity, but on 
receipt of an order will send a man with a seed separating 
machine to a cull heap near some packing-house, secure 
the amount of seed desired, and forward immediately to 
the purchaser in a wet condition. Such seed must be 
planted at once. The price is usually from $18 to $25 a 
bushel, which contains about 35,000 seeds. Pomelo seed 
is secured either locally or from Cuba. It will stand dry- 
ing to a small extent only. Rough lemon seed may be 
handled much like sour orange seed. 

After the freeze of January, 1913, it was found by experi- 
ment that the seed in oranges which had been frozen was 
viable, although dark in color. Almost as good germina- 
tion was secured with seed from frozen as from sound 
oranges. 

It is an established custom in California to grow citrus 
seedlings under a lath shelter, although one large nursery- 
man near the coast has broken away from this custom and 
has secured good results by planting entirely in the open. 
In the hot interior some shelter is necessary, but the trees 
grow in height faster and are ready for market quicker 
if grown under shelter anywhere. The shelters are cov- 
ered with one-inch laths alternating with one-inch open- 
ings, supported by uprights set at convenient distances. 



The Citrus Nursery 87 

The lath are usually nailed to cross pieces in sections of 
suitable size to be handled by two men. The shelter rests 
about eight feet from the ground and the lath should run 
north and south. 

The soil for the seed-bed should be deep, sandy loam, 
free from stones and well-drained. Virgin soil is best, 
but if that is not obtainable, good, rich grain land will 
answer. It should of course be worked up into a fine 
state of tilth, leveled, and slightly firmed with a light roller. 
If dry seed is used, it should be soaked for twenty-four 
hours before planting. If the bed is to be irrigated by 
running water through furrows, the ground is laid off in 
rows twelve inches wide with very shallow furrows about 
eight or ten inches wide. A broad, shallow, slow stream 
of water is needed to soak through such rows. The seed is 
planted broadcast on these wide rows, every sixth row being 
left vacant for a walk. In case the bed is watered from 
above by automatic sprinklers, as is usually the case, 
the seed is broadcasted over the entire surface of the 
ground except for a twelve-inch path every ten feet. In 
some cases the seed is simply planted about one inch deep 
in the loose soil and then thoroughly watered. In most 
cases, however, the seed is gently pressed into the soil 
•with a board and covered from \ to 1 inch dee]) with 
clean coarse river sand especially provided for the purpose. 
'This covering of sand prevents the ground from baking 
and also keeps the surface dry. The seeds are placed 
about one inch apart each way and if half of them or even 
an average of thirty to the square foot grow, the stand is 
considered satisfactory. 

One of the greatest dangers to the seed-bed is the pos- 



88 Citrus Fruits 

sibility of infestation by the " damp-off" fungi. This 
disease works very rapidly, covering a large area in a single 
night and killing the seedlings just after they come up. 
This trouble may usually be prevented by keeping the 
surface of the ground as dry as the requirements of the 
seedlings will permit. The covering of sand allows the 
water to pass through to the roots while the surface dries 
again very quickly. The usual time of planting is April, 
and most of the plants should be large enough to sell 
one year after planting. 

After the seedlings are two months old they may be 
watered more generously every two or three weeks as 
necessary. All weeds should be kept out of the beds, and 
a sharp watch must be kept for gophers, moles, and ants. 
The plants are sold for from $20 to $50 a thousand when 
they are about a foot high. The beds are usually gone 
over twice, the smaller plants remaining for two years. 
It is hardly necessary to point out that the plants first 
pulled from the bed are much more desirable than those 
which require two years to reach marketable size. In 
ordering seed-bed stock "first pull" plants should always 
be specified. 

No manure or compost of any kind should be used in the 
seed-beds for fear of encouraging the "damp-off" fungi, 
which are usually more serious in proportion to the amount 
of freshly decaying organic matter in the soil. A moderate 
dressing of commercial fertilizer high in nitrogen will 
accelerate the growth of the plants. Often no fertilizer 
is used. 

After the seedlings have safely passed the stage when 
they are liable to damp-off, they may become infected 



The Citrus Nursery 89 

with brown-rot gum-disease. In such cases they will 
exude gum just above the ground and may be girdled 
and killed. Where there is any large amount of such 
gumming, a thorough spraying with bordeaux-mixture 
is recommended. Sour-stock is very resistant to gum- 
disease in the orchard, but this is not always the case in 
the seed-bed. 

When seed-bed stock is to be dug, the soil is first thor- 




Fig. 25. — Citrus seed-bed in the open. 

oughly wet, the roots slightly loosened with a long tined 
spading-fork, and the plants drawn by hand. A varying 
proportion of the plants will have a crooked or Z-shaped 
tap-root known as "bench-root." When the seed-coat is 
tough, the root has difficulty in piercing it and often makes 
several turns before getting out. This may be partly pre- 
vented by soaking the seed over-night before planting. 
All such plants are inferior and should be discarded. All 



00 



Citrus Fruits 




Fig. 26.- 



Bench-rooted orange 
seedling. 



plants which have gum-dis- 
ease should also be thrown 
away. After grading, the 
plants are tied in bunches and 
their tops chopped off squarely 
with a hatchet about eight 
inchesabove the crowns. They 
are then packed tightly in 
boxes or bags with the tops ex- 
posed and with moist sphag- 
num moss about the roots. 

Citrus seed-beds are likely 
to become infested with scale- 
insects or other pests, espe- 
cially if situated near infested 
orchards. In many counties, 
horticultural inspectors have 
strict regulations in regard 
to the admission of nursery- 
stock shipped from other 
counties. Such local regu- 
lations are by no means uni- 
form for the whole state. It 
is wise to confer with the ap- 
propriate officer in each case 
before the plants are dug in 
order to learn just what kind 
of treatment will be required. 
Usually the plants are dipped, 
all but the roots, in the fol- 
lowing solution : 



The Citrus Nursery 91 

Resin 20 lb. 

Caustic Soda 8 lb. 

Fish Oil 3 pt. 

Water 100 gal. 



PLANTING SEED-BED STOCK 

For the planting of seed-bed stock, a deep rich loam, 
free from stones, should be selected. It should contain 
just enough clay to stick together well when the trees are 
balled. The site for the planting should be as free from 
frost as possible, as newly set buds are very susceptible to 
cold. The stock is planted eighteen inches apart in rows 
three and a half or four feet apart. Especial emphasis 
is here laid upon the fact that the roots of citrus plants are 
very susceptible to injury from drying, and if a plant is 
left in the sun, with its roots exposed, for more than a few 
moments, it is almost sure to fail to grow. The best plan 
is to take all the plants into the field in the boxes of 
sphagnum covered with wet sacks. Only a few should 
be handled at a time and in such a way as not to expose 
the roots at all. The plants are usually set with a dibble 
or spade, great care being taken to get the roots in straight 
and not to set the plants deeper than they grew in the seed- 
bed. In planting citrus trees of any size or kind, it is a 
safe rule not to vary the depth of planting. The soil 
around the plants should be well firmed to bring the roots 
in close contact with moist earth. Irrigation water 
should follow the planters down each row as the work 
proceeds. After the soil is well irrigated the plantation 
should be gone over and those plants which on account of 
their small size did not have a part of the top trimmed off 



92 Citrus Fruits 

at the seed-bed should be cut back about fifty per cent. 
These small plants which escaped the trimmer's hatchet 
are almost sure to die unless headed back in the same 
proportion as the others. 

Budding stock handled as described, and properly culti- 
vated and irrigated, should be large enough to bud at the 
end of one or two years, usually eighteen months. An 
application of about one-half ton per acre of special nursery 
stock commercial fertilizer will save time in growing the 
plants to budding size. Every effort should be made to 
encourage a vigorous growth. It is false economy to 
bud seedlings which are too small ; the ideal size being 
from | to i^ inch in diameter three inches from the 
ground. 

PROPAGATION 

Many writers make the statement that citrus trees are 
propagated by budding, grafting, cuttage, and layerage. 
This is somewhat misleading, inasmuch as budding is the 
universal method employed in America. Lemon cuttings 
may be made to root, but orange cuttings are so difficult 
as to be out of the question entirely. The few lemon trees 
that have been grown from cuttings have been inferior 
and have mostly passed out of existence. Layering 
is never used and grafting is very rarely resorted to except 
in the case of old trees which have been frozen to the 
ground. Most old trees which are top-worked are budded. 
The writer has seen buds successfully placed directly into 
orange trunks which were a foot and a half in diameter, 
although such a practice is rare and not to be recom- 
mended. 



The Citrus Nursery 



93 



Cutting Bud-ivood 

The success of the 
citrus orchard depends 
to a very large extent 
upon the care used in 
cutting the bud-wood. 
This is due to the fact 
that a certain propor- 
tion of the trees in 
many orchards belong 
to undesirable types. 
This particular phase 
of the subject will be 
reserved for a more 
extended discussion in 
Chapter VII. Suffice 
it to say here that too 
much pains can hardly 
be taken in selecting 
the mother trees from 
which the buds are to 
be cut. 

Citrus buds should 
be cut from round, 
plump wood taken from 
the fruiting branches. 
It is usually easy to 
find plenty of suitable 
bud-wood on lemon 
trees, but with oranges, 




Fig. 27. — Orange bud-wood. 



94 Citrus Fruits 

and especially Navel oranges, this is often difficult for 
the reason that the best trees are devoting their energies 
to bearing rather than to growing plump bud-sticks. The 
small angular fruiting twigs are not large enough to use to 
advantage. On this account it becomes necessary to give 
Navel mother trees a preparatory pruning a year before the 
buds are wanted. The trees are thinned out and cut back 
uniformly in all parts in order that there may be a more 
vigorous growth of fruiting wood. This pruning should 
not be carried too far or water-sprouts may result. Bud- 
sticks about a foot long and the size of a lead pencil made 
up of one- and two-year-old wood is best. Current growth 
is too tender and three-year-old wood contains many blind 
buds or buds which will be very slow to start. Uniformity 
in starting the buds is much to be desired, and the more 
care is used in collecting buds of the same degree of matu- 
rity, the more uniform the nursery will be. The leaves 
are cut off, leaving a short stub for a handle. The cutting 
may be done in mid-winter and the accumulated wood 
buried in slightly moistened sand for two or three months. 
The wood will cure and callous on the lower end, and cured 
wood is supposed to give more uniform results. Most 
budders prefer to keep the bud-wood in boxes of moist 
sphagnum because the sand will dull the budding knives 
unless the wood is carefully washed. It is not necessary 
to cure the buds, but it is often more convenient to cut 
the buds all at one time and keep them until used. It is 
best to select bud-wood as free from thorns as possible for 
the reasons given in Chapter III. 

A great deal of argument has been indulged in over the 
question of whether buds from sucker growths or water- 



The Citrus Nursery 95 

sprouts are as desirable as buds from the fruiting brush. 
It is unwise to use buds from rank growing water-sprouts 
because an excess of food is one of the chief causes of 
variation ; and as these buds have a great excess of food, 
they are somewhat more likely to grow into sporting trees 
than are buds from fruit wood. This does not mean, how- 
ever, that good trees have not been grown and may not 
again be grown from sucker buds. We simply take the 
position that it is an unwise policy for the reason given. 

Time of Budding 

Citrus stock may be budded at any time of the year or 
whenever the bark will slip, but the best time is during 
the months of October and November, in which case the 
buds usually remain dormant until spring. Stocks upon 
which the buds fail, may be rebudded in April or May. It 
often happens, unfortunately, that a certain proportion 
of fall set buds start into growth immediately, thus ex- 
posing a few inches of very tender growth to the dangers 
of winter. In such a case, the number of orchard heaters 
set in the nursery should be increased and the fires started 
at the first indication of frost. 

Method of Budding 

In California, the usual method of insertion is the shield 
or T method. The bud-stick is grasped firmly with the 
tip toward the operator. With a very sharp budding knife 
the bud is cut by inserting the blade about one-half inch 
below and drawing it beneath the bud and out about 
one-half inch above, thus cutting a bud about one inch 



96 



Citrus Fruits 



long. The bud is held firmly between the thumb and 
the knife blade while a slit is cut in the bark of the stock 
about three inches above the ground and one-half inch 
long. At the top of .this slit, a cross cut is made with the 
edge of the blade of the knife inclined downward. The 
bud is then inserted in this slit, being careful to have 
the leaf scar or bottom of the bud down. The back of 

the point of the knife 
is then placed on the 
leafscar and the bud 
pushed down until 
the upper end is be- 
low the cross cut, 
and in any event un- 
til the pressure of the 
bud begins to split 
the bark beyond the 
previously made 
slit. A strip of waxed 
cloth isthenVrapped 
quite firmly around 
the stock five or six 
times so as to cover 
the bud completely. 
Some budders prefer to leave the eye exposed but this is 
not necessary. Buds are usually set on any side as re- 
gards the points of the compass, or in other words, the side 
most convenient to the budder. The bark usually slips, 
and the buds take better, directly under a small branch. 
Some budders prefer to use the inverted T method. 
The cross cut in the bark of the stock is made lower and 




Fig. 28. — Cutting abud. 



The Citrus Nursery 



97 



the bud pushed upward instead of downward into place. 
The inverted T is somewhat better for fall budding, as the 
cross cut or obstruction when placed below the bud tends 
to produce a quiescent state which is desired during 
winter. The cross cut when placed above the bud tends 
to produce a strong lateral growth and is therefore best 
for spring budding. 

Most seedlings 
tend to branch close 
to the ground and as 
a result buds are 
often placed quite 
close to the ground. 
This is a mistake in 
most cases, especially 
when using sour 
orange as a stock. 
This stock owes its 
popularity largely to 
its resistance to gum- 
disease, but when 
buds are placed low 
this resistance is 
much reduced. The object should be to keep the 
wood of the scion as far from the ground as practic- 
able in order to avoid gum-disease infection, which 
comes from the soil. If, on the other hand, buds are 
placed too high, a crooked and ugly trunk will result. 
While high budded trees are less comely and do not sell 
as well on account of the crook in the trunk, still they are 
the more to be desired, especially when intended to be 




Fig. 29. — Making incision in stock. 



98 



Citrus Fruits 



planted on heavy soils or near the coast, where gum-dis- 
ease is prevalent. 

After about ten days, the buds should be unwrapped and 
examined. If they have taken, as evidenced by a grayish 
line of callous tissue forming around the edges, the wrap- 
pings are loosened, to be removed entirely after about 
thirty days in the case of the fall buds and twenty days 

in the case of spring 
buds, or whenever 
the bud is well 
healed. 

In the case of fall 
buds which have re- 
mained dormant, as 
they should during 
winter, the tops of 
the stock are cut 
back in the spring to 
within six inches of 
the buds in order to 
increase the sap pres- 
sure and force them 
into a more uni- 
form growth. The 
promptness with which a bud starts depends to some 
extent on its age and position on the bud-stick. Uni- 
formity of growth is greatly to be desired in the 
nursery, and such cutting back tends to force all the 
buds to start more nearly at the same time. The six 
inches or more of stock which is left affords a certain pro- 
tection to the young shoot and reduces the possibility 




Fig. 30. — Inserting bud. 



The Citrus Nursery 



99 



of the bud being involved in any dying back which may 
occur. After the young shoot has grown eight or ten 
inches the stub of the stock is sawed off smoothly, the 
edges trimmed with a sharp knife, and the cut surface 
covered with liquid grafting wax. 

In the case of spring set buds, the same custom prevails 
except that some- 
times the stocks are 
only partially cut 
back at first. With 
late set buds there 
is sometimes a dan- 
ger of the superabun- 
dance of sap during 
hot weather "drown- 
ing out" the buds if 
all the top of the 
stock is removed too 
suddenly. Occasion- 
ally the tops are 
"lopped" or cut half 
through and bent 
down in the middles, 
in order to gradually change the flow of the sap. They 
are removed entirely after a month or six weeks. 

Citrus budding is often done by expert budders by con- 
tract at about $10 a thousand, the budder guaranteeing 
a 95 per cent stand and furnishing his own buds, wrapping 
cloth, and the like. Eight and a half dollars a thousand 
is a common price when buds are furnished. This of 
course applies to regular fall budding. 




Fig. 31. — Tying inserted bud. 



100 Citrus Fruits 

Training the Young Tree 

In order to insure a perfectly straight trunk the young 
trees are trained to stakes. The stakes may be set soon 
after the buds have started growth. The stakes used in 
California are ordinary building laths. They are driven 
into the ground close by the stock on the side next the 
scion. As the young shoot grows it is tied to the stake 
with soft raffia. A tie is made every three inches, the 
raffia being drawn up snugly under a leaf. The rough 
unfinished surface of the lath is an advantage, as it pre- 
vents the raffia from slipping down. Careful attention 
to tying is necessary in order to secure straight trunks. 
While going over the trees for tying it is also necessary 
to remove any side branches which may put out, as well 
as the numerous suckers which arise from below the bud. 
These sprouts should be rubbed off with the thumb while 
still very young, and this necessitates going over the trees 
every three or four weeks during the first summer. 

Nursery trees should be allowed to grow three feet tall 
and then headed back to 27 or 30 inches. This will insure 
the main branches being set upon stronger wood than if 
the terminal bud was pinched as soon as it reached the 
desired height. Branches which are to be the framework 
of the future tree are encouraged to put out on all sides 
and distributed over the upper twelve inches. From 
three to six main branches are sufficient. The old custom 
was to allow the framework branches to arise from 
near the same point. Experience has shown that such 
branches split down badly and require much bolting when 
the trees grow old. This is being abandoned, especially 



The Citrus Nursery 



101 



with lemon trees, in favor of the less comely but more de- 
sirable distribution of main branches. 



.*"*•* " -. 'fjf 2 - • r v 




Fig. 32. — Orange buds in nursery row tied to lath stakes. 

Often a tree will make several growths before it reaches 
the top of the stake. The end of each growth is marked 
by a ring or node of thickened tissue. There is a wide- 



102 Citrus Fruits 

spread belief that a tree with several of these nodes on the 
trunk is to be preferred to one which made one growth to 
the top of the stake. The reason assigned is that it indi- 
cates slow growing and heavy fruiting qualities. It is 
doubtful whether there is sufficient basis in fact for this 
belief, although there are some arguments in its favor. It 
is not unlikely that in the case of the Washington Navel 
orange there may be some correlation between the num- 
ber of nodes and fruitfulness, but this is probably not the 
case with lemons. 

The citrus nursery should be thoroughly cultivated and 
irrigated and the trees kept in vigorous growth. Com- 
mercial fertilizer should be applied liberally, usually a 
ton to a ton and a half to the acre of a complete fertilizer 
high in nitrogen. One or two years are required to grow 
a marketable tree. We find, therefore, that a total of from 
four to six years is required from planting the seed to set- 
ting the trees in orchard form. 

Trees are graded and priced according to caliper measure- 
ment one inch above the bud. Well-grown one-year trees 
are often acceptable, but usually two-year trees are much 
better. Prices in California vary from fifty cents to one 
dollar and a quarter a tree. 

PREPARING TREES FOR SHIPMENT 

Citrus trees may be dug with naked roots, cut back to 
the trunk, shipped long distances, and planted with perfect 
success ; but on account of the fact that it is difficult to 
always see that the tender roots are not exposed, there is 
much loss from the carelessness of laborers, and the 



The Citrus Nursery 



103 



custom of balling trees has become general in California. 
Balled trees are much less perishable, may be handled with 
more assurance, do not require all the top to be removed, 
do not need to be reheaded, and make a somewhat better 
showing the first year. On the other hand, the cost of 





Fig. 33. — Healing of the bud union. 

balling is great and the freight on thirty to forty pounds 
of earth with each tree adds considerably to the cost. 

It is recommended, therefore, that trees be balled where 
the distance to be transported is short or when inexperi- 
enced men are to do the planting. Where the owner is 
able to look after the planting personally the trees may be 
dug with naked roots and a considerable saving on freight 
and expense of balling will result. Where trees are to be 
moved only a short distance, as from one part of a ranch 



104 



Citrus Fruits 



to another, the following method is sometimes used. 
Short sections of ten-inch pipe are placed over the trees 
and driven into the ground, thus cutting all roots but 
the tap-root, which is cut with a spade. The trees are 




Fig. 34. — Balling orange trees in the nursery. 



then moved and the core of earth containing the trees is 
slipped out of the pipe into the hole prepared, the pipes 
being used again and again. 

When trees are to be balled, a trench a foot wide and 
fifteen inches deep is dug alongside of a row of trees and 
with careful work the tap-root may be cut and the tree 



The Citrus Nursery 105 

lifted with a ball of earth. This is carefully wrapped in 
old sacking and firmly tied with strong cord. The top is 
cut back somewhat, the leaves removed from the trunk, 
and the trees are ready for shipment. A bailer and tyer 
work together and in good soil should turn out about one 
hundred and seventy-five trees a day. Counting the men 
engaged in digging trenches and defoliating, a crew of 
twenty-five men should dig and ball about fifty trees a 
day for each man in the crew. When a few balled trees 
are shipped, they must be boxed at considerable expense. 
In the case of carload lots, they are simply stacked closely 
together in ordinary box cars, the balls resting on a layer 
of moist straw on the bottom of the car. En route the 
balls should be kept moist, but not so wet as to start 
growth. California now produces upward of a million 
and a quarter citrus trees a year, many of which are 
shipped to various foreign countries including South 
Africa, New Zealand, and India. Foreign shipments 
always go forward with bare roots firmly packed in 
sphagnum moss. 



CHAPTER VI 

HORTICULTURAL INSPECTION AND 
QUARANTINE 

California has had much experience with horticultural 
statutes. Many different laws have been passed and 
amended from time to time during the last thirty years. 
During this time there has been hardly a session of the 
state legislature which has not changed the law in some 
particulars. The citrus industry is so vitally concerned 
with the activities of the State Commission of Horticul- 
ture as to warrant a description of this important agency. 

In March, 1908, the State Commissioner of Horticulture 
published a handbook containing all the laws together 
with the court decisions and legal opinions relating thereto, 
corrected to that date. More recent laws, together with 
a number of quarantine orders, may be found in the Com- 
missioner's "Monthly Bulletin," Vol. II, pp. 337-351, 1913. 

The ordinances of the different counties relating to the 
movement of nursery stock from one county to another 
may be secured from the respective County Horticultural 
Commissioners. 

THE STATE COMMISSIONER OF HORTICULTURE 

This official is appointed by the Governor for a term of 
four years or until his successor is appointed. 

106 



Horticultural Inspection and Quarantine 107 

While the state law, approved April 26, 1911, directs 
the Commissioner to collect books, pamphlets, and periodi- 
cals and acquire all possible information by correspondence 
for the furtherance of the horticultural industries, still 
his principal function is that of a police officer. He is 
by virtue of his position the state horticultural quarantine 
officer, and as such is responsible for the rigid exclusion 
from the state of injurious insects and plant diseases, and 
the prevention of any further dissemination of such pests as 
are already established in certain localities within the state. 

In order to enforce the state quarantine law approved 
January 2, 1912, the Commissioner maintains an office 
with a force of inspectors at San Francisco, another at Los 
Angeles, and a third at San Diego. These inspectors go 
through the cargoes of every ship arriving from any foreign 
port or from Honolulu, and the baggage of every passenger. 
If any plants, fruits, or seeds are found to be infested with 
injurious insects or diseases, they are fumigated at the 
expense of the owner, or treated in such a way as to kill 
the pests. If this is impracticable, the plants are destroyed 
or, at the option of the owner, returned whence they came. 
In some cases the State Commissioner may, with the 
written approval of the Governor, issue a quarantine order 
against certain fruits or plants from certain countries. 
Such articles are then considered contraband and, if an 
attempt is made to introduce them, are confiscated and 
destroyed by the inspectors regardless of whether they are 
infested or not. 

The State Commissioner may appoint the County Horti- 
cultural Commissioners or their agents special quarantine 
officers for the purpose of inspecting shipments coming 



108 Citrus Fruits 

from the Eastern states or Europe and billed to interior 
points in California. The common carriers are by law 
forbidden to deliver to a consignee within the state any 
shipment of horticultural goods until such shipment has 
been inspected, declared free from pests, and formally 
released in writing by a duly appointed horticultural in- 




Fig. 35. — A shipment of defoliated balled orange trees. 

spector. The inspector may exercise his discretion in re- 
gard to the disposition of infested shipments. He may rid 
the plants of pests by fumigation or other means and then 
release them upon payment of the costs ; or if in his judg- 
ment the infestation is severe or the pest particularly dan- 
gerous, he may destroy the goods or cause their reshipment 
out of the state. 

As an example of a quarantine order now in force we may 



Horticultural Inspection and Quarantine 109 

cite Order No. 21, which forbids the shipment of any of the 
forty listed host plants of the citrus white fly, Aleyrodes 
citri and Aleyrodes nubifera, from North Carolina, South 
Carolina, Georgia, Florida, Alabama, Mississippi, Loui- 
siana, and Texas into the state of California. This order 
prevents California growers from securing nursery stock 
or scions of new varieties in any of the above mentioned 
states. By special arrangement, however, the citrus seeds 
planted by nurserymen which come from Florida and Cuba 
are admitted, provided they are sent in care of some desig- 
nated agent of the Commission, who fumigates them be- 
fore delivery to consignee. 

Another quarantine order prevents the importation from 
Hawaii of mangoes, oranges, avocados, and other fruits 
which are hosts of the Mediterranean fruit fly, Ceratitis 
capitata. Still another order forbids the shipment into 
California from Mexico of oranges, mangoes, or other fruits 
which are hosts of the Mexican orange maggot, Tripeta 
ludens. These latter, however, have now been superseded 
by national quarantine orders. 

It has long been the custom of the State Commissioner 
of Horticulture to hold two meetings each year which are 
known as State Fruit Growers' conventions. One meeting 
is usually held at some convenient place in the northern 
part of the state and the other in the southern part. The 
proceedings of these conventions are brought together, 
edited, published, and distributed free by the State Com- 
missioner. The meeting held at Davis in June, 1914, was 
the forty-fifth such convention. The printed proceed- 
ings of these conventions represent a very fertile source of 
information for the student of California citriculture. 



110 Citrus Fruits 



THE COUNTY COMMISSIONERS OF HORTICULTURE 

The California State law providing for County Horti- 
cultural Commissioners has been amended many times. 
The present law, approved March 25, 1911, provides: 
that whenever a petition, setting forth the legitimate need 
for a Commissioner and signed by twenty-five or more 
resident freeholders who are possessed of horticultural 
properties, is presented to the county board of super- 
visors, said supervisors are required to appoint a County 
Horticultural Commissioner from the list of eligibles, who 
must have passed the examinations held by the state 
board of horticultural examiners. The term of the County 
Commissioner is four years. 

Many of the duties of the County Commissioner are pre- 
scribed by county ordinances, and these vary in the differ- 
ent counties. The Commissioner is usually required to 
keep informed as to the particular localities within the 
county where pest infestation is serious. He must have 
the orchards and ornamental plantings inspected, and when 
in his judgment the scale insects have increased in any 
orchard until they constitute a public nuisance, he must 
serve written notice on the owner to abate the nuisance 
by fumigating, spraying, or otherwise within a certain time 
limit. If this order is not complied with, the Commis- 
sioner may enter the premises and abate the nuisance, the 
cost of such work becoming a lien on the property. If the 
cost of the work is not paid, enough of the property may 
be sold at public auction to satisfy the lien. 

Such ordinances have been tested in the courts and 



Horticultural Inspection and Quarantine 1 1 1 

found constitutional, the acts of the County Commissioners 
being upheld in each instance. 

County Commissioners may appoint local inspectors 
in outlying towns and fruit districts within the county. 
The Commissioner also renders an annual report to the 
State Commissioner and a monthly report to the board 
of supervisors of his county. 

As special state quarantine officers it is the duty of the 
County Commissioners and their agents to inspect every 
shipment originating outside of the state, as well as those 
coming from other parts of the state which arrive in their 
territory. 

It is also the duty of the Commissioner to inspect every 
outgoing shipment of horticultural goods before it is ac- 
cepted by a common carrier. The law requires common 
carriers to accept only such packages or lots as bear a 
statement signed by the Commissioner or his agent 
certifying that the goods are free from injurious pests. 
We find, therefore, that every package of horticultural 
goods is inspected twice, once at the point of shipment 
and again at the place of delivery. 

THE NECESSITY FOR INSPECTION 

The question may arise in the mind of the reader as to 
whether this complex system of quarantine and inspection 
is worth while. The answer to this question may be found 
in the following quotation from California Experiment 
Station Bulletin No. 214, by H. J. Quayle. 

" That insect pests are one of the important factors in 
the citrus fruit industry of California is shown by the fact 



112 



Citrus Fruits 



that more than half a million dollars are expended annually 
in their control. This amount includes only what is actu- 
ally expended in fumigation and spraying, and does not 
take into consideration the loss of fruit from improperly 
treated trees or trees not treated at all. The cost of fumi- 




Fiu. 30. — Two-year-old orange trees balled, ready for market. 

gation in one county alone amounts to $200,000 annually. 
Furthermore each county maintains a horticultural Com- 
missioner, and many of them a corps of inspectors, pri- 
marily on account of insect enemies, who are charged with 
the quarantine and inspection work, the cost of which in 
some of the counties may run as high as $25,000 annually. 
All of this vigilance seems to be warranted by thirty 



Horticultural Inspection and Quarantine 113 

years' experience of the most important fruit section of the 
United States. 

" It has been estimated that the average cost of fumiga- 
tion per tree, taking the whole of the citrus belt, amounts 
to about 30 or 40 cents, which means an expense of approx- 
imately $30 to $40 per acre, and this is done on an average 
about every other year. This is intensive insect fighting, 
but when the improved market value of the fruit is con- 
sidered, it is money judiciously spent with such a valuable 
crop as the orange or lemon." 

In conclusion we may say that the benefits of exemption 
from scale insects is clearly reflected in the prices asked 
for land and bearing orchards in scale-free localities. 
The annual tax of 15 to 20 cents a tree for fumigation is 
especially unwelcome and growers in scale-free localities 
do well to exercise every possible precaution to prevent 
the introduction and establishment of such relentless 
tax-gatherers as the insect pests and plant diseases have 
proved themselves to be. 



CHAPTER VII 

IMPROVEMENT OF CITRUS TREES BY 
BREEDING 

The production of citrus fruits in California and 
Florida is increasing at a rapid rate. The shipments 
from these two states for the season 1913-14 reached a 
total of about sixty thousand cars. Thousands of acres of 
young orchards are just coming into bearing, and the near 
future will undoubtedly witness a large increase in produc- 
tion. The problem of how to make a profit in the business 
in spite of the heavy production will loom large in the 
future. 

Undoubtedly a great deal may be accomplished through 
the marketing organizations by securing better distribu- 
tion of the fruit and increased consumption through proper 
advertising. Yet it is a fact that much loss is at present 
due to a lack of varieties which are well suited to the cli- 
matic and soil conditions under which they are grown, 
to ignorance in regard to adaptation of varieties, and to 
sports or aberrant forms which occur throughout the 
citrus growing districts much more commonly than is 
generally recognized. 

Through carelessness or ignorance in the selection of 
bud-wood many poor or even worthless types have been 

114 



Improvement of Citrus Trees by Breeding 115 

propagated and widely planted. The poor financial show- 
ing made by many orchards is due largely to the prepon- 
derance of trees belonging to aberrant forms. 

While some progress may be made toward improved 
varieties through hybridization, the writer is strongly of 
the opinion that much better and quicker results are to be 
secured through the careful selection of desirable bud- 
sports which occur rather frequently on trees of the old 
standard varieties. 

HYBRIDIZATION 

The object of hybridization is to secure seedlings which 
combine the desirable characteristics of two or more parent 
trees. The flowers of the selected parent trees are cross- 
pollinated by hand, using great care in excluding foreign 

pollen. 

Cross-pollination is a very easy operation and may be 
performed successfully by any one willing to use a little 
care and perseverance. The structure of the citrus 
flower is very simple and a knowledge of the functions of 
the different parts is easily acquired by the study of the 
diagram at Fig. 14. The essential organs of the flower 
are the stamens and pistil. The anthers bear the pollen 
grains, each one of which when placed on the stigma will 
germinate and send a tube down through the style and into 
the ovary. The male nucleus from the pollen gram passes 
down through this tube and comes in contact with the 
female egg-cell of the ovule with which it fuses, thus bring- 
ing about fertilization and the combination of the charac- 
ters of the two parents. A separate pollen grain is needed 



116 Citrus Fruits 

for each seed, and the parental characters may be com- 
bined in a different way in each case. After the ovaries 
have been fertilized they grow into viable seeds. It is 
not always necessary for citrus flowers to be pollinated and 
fertilized in order to produce fruit. The Navel orange for 
instance rarely contains seeds and on that account is 
known as a parthenocarpic fruit. 

When cross-pollination is accurately performed, it is 
necessary to place paper bags over the blossoms which 
are to be used as a source of pollen, before the buds open. 
This is necessary in order to prevent the possibility of the 
mixing of pollen by insects. The pollen may be gathered 
and dried on papers and stored in small bottles for use, 
but it is often convenient to cut the twigs, bag and all, and 
carry them to the tree which is to be used as a female 
parent. Large buds just ready to open should be selected 
and all the smaller buds and open flowers on the twig 
removed. The petals are pried apart with a small pair 
of forceps and an anther bearing ripe pollen is taken 
from a blossom within one of the bags and placed firmly 
upon the stigma, pressing it down into the drop of white 
mucilage. If no mucilage appears on the stigma, it is 
evidence that the bud is immature. The camel's-hair 
brush commonly used in cross-pollinating fruits is not 
satisfactory in citrus work on account of the copious 
excretion of mucilage by the stigma. It is wise to cross- 
pollinate several buds on each twig, as many are apt to 
drop off. After the pollen has been placed on the stigma, 
the small immature anthers must be removed from the 
flower for fear that the pollen produced later by them may 
interfere with the results. In the case of the Navel orange 



Improvement of Citrus Trees by Breeding 117 

this is not necessary, as the anthers do not produce 
pollen. After the operation has been completed a paper 
bag should be placed over the twig and tied with string. 
After two or three weeks the paper bags may be replaced 
by cheesecloth bags, which remain on till the fruit is 
picked for seed. 

The value of crosses or hybrids produced in this way 
cannot be determined for several years, or until the trees 




Fig. 37. — Type of standard Washington Navel orange. 

have been reared to fruiting. By top-working buds taken 
from the young seedlings into old trees the fruit may 
be secured earlier. 

The improvement of citrus fruits by this method is very 
slow and the results uncertain. Moreover it is doubtful 
whether an entirely new variety of orange or lemon, how- 
ever good, could gain much recognition in California in the 
face of the popularity of the Navel and Valencia oranges 
and the Eureka lemon. The history of the industry in 
California has shown a constant elimination of varieties 



118 Citrus Fruits 

rather than the acquisition of new ones. The greatest 
field for hybridization work lies with the pomelos. There 
is at present no thoroughly satisfactory variety of pomelo 
suited to the climatic and soil conditions of California. 
The feeling of the growers in regard to better varieties of 
oranges and lemons was clearly shown some years ago 
when E. J. Wickson sent out a circular letter to determine 
the most urgent needs along the line of citrus breeding. 
The response of the growers was significant. They re- 
plied that what was needed most was a Washington 
Navel which would color earlier ; a Navel which would 
hang on the tree like a Valencia ; a Navel that would 
not split ; a Navel that would not puff ; and a Navel 
more hardy to frost. Some growers wanted a Valencia 
that would not turn green a second time, or a Valencia 
without seeds. 

The most expeditious way of securing the results desired 
by the growers is by selecting and propagating those sports 
from the varieties mentioned which approach most closely 
the desired types. Such bud variations occur quite fre- 
quently in citrus trees. They present a vast field for the 
work of improvement of types. 

VEGETATIVE MUTATIONS OR BUD-SPORTS 

Citrus trees, in common with other plants, are observed 
to vary in several ways. There are fluctuations or un- 
stable differences which come and go in response to the 
various complex stimuli produced by changing conditions 
of soil and climate, or, in other words, changes of food and 
environment. There are also sudden changes known as 



Improvement of Citrus Trees by Breeding 119 

mutations which result in new forms that are stable and 
form the starting point of new strains or varieties. 

Fluctuations are of two kinds, regular and fortuitous. 
As an example of regular fluctuation we may cite certain 
influences of climate and soil which produce substantially 




Fig. 38. — Washington Navel oranges showing fluctuations in the navel; 
such variations cannot be preserved by budding. 



the same effect upon every plant of the same variety. 
Navel oranges grown in the hot Imperial Valley are much 
redder in color than those grown within the influence of 
ocean fogs near the coast. Oranges grown on light sandy 
soil are of larger size than those grown on stiff clay soil. 
Under the head of fortuitous variations may be included 



120 Citrus Fruits 

many of the common malforms and monstrosities such as 
double oranges, oranges with protruding navels, fingered 
lemons, and various other teratological curiosities which 
may be found in the cull-heaps near the packing-houses. 

Mutations occur as sporting branches which show a 
different combination of characters from the rest of the 
tree. The immediate cause of mutations is not at present 
understood. They originate during the division of some 
single cell in the vegetative tissue which results in 
daughter cells containing the same determiners for char- 
acters but segregated and recombined in such a way as to 
produce characters visibly different from those of the 
parent stock. Thus appear new characters which, from 
the standpoint of the man who is growing the fruit, may 
be either valuable, neutral, or objectionable. 

When a shoot arises from tissue which has been formed 
by mutating cells, the shoot represents a new variety or 
sport variety which may be propagated by the ordinary 
method of budding. Sometimes more or less reversion to 
the old type occurs in the young trees. The cause of this 
has been observed to be due to the mode of origin of the 
sporting shoot. If the shoot arises from within the area of 
mutating cells in such a way that only these cells are used 
in the forming bud, then the resulting shoot will be com- 
posed exclusively of new cells and the sport may be prop- 
agated true without reversion. If on the other hand the 
shoot arises on the edge of the area of new cells in such a 
way as to include both kinds of cells in its structure, then 
there arises a mixed branch or " sectorial chimera " which 
may be expected to constantly produce branches of various 
kinds. Some will be like the original plant, some like the 



Improvement of Citrus Trees by Breeding 121 

new form, and some in turn will be mixed depending upon 
the kind of cells occurring at the point where each bud 
has its origin. The " Nomadic Albinism " described by 
Savastano 1 was probably a sectorial chimera. 




Fig. 39. — Variegated sport. Note white areas in leaves. 
Volckamer's " Hesperides," 1695. 



From 



Sectorial chimeras are not uncommonly met with in 
citrus trees. The writer has found excellent specimens 
in commercial orchards and some have been kept under 

1 An. del. Stazione de Agrum. e. Fruit. Vol. 1, 1911, XXIX. 



122 Citrus Fruits 

constant observation and study for five years. A Valen- 
cia orange tree in an orchard near Whittier was evidently 
propagated from a bud with mixed cells, for it still bears 
year after year on all its branches both typical Valencia 
oranges and a small, very rough, and worthless mutation. 
A twig here and there will produce typical Valencias, while 




Fig. 40. — A variegated sport of Valencia orange. Notice white margin 

of leaves. 

others will produce curious mixed oranges having certain 
sectors of the fruits composed of mutant tissue. The 
owner of this tree endeavored to get rid of the worthless 
type by pruning it out, but mutant branches continually 
returned, and it requires frequent pruning to keep them 
suppressed. In this case the mutant tissue happens to 
occur irregularly scattered or mixed with the tissue of the 



Improvement of Citrus Trees by Breeding 123 

original form. Such a mixture has been called a " hyper- 
chimera." ] 

Mutations often occur in the cells which begin the 
formation of the minute ovaries in the blossom buds. As 
the ovary grows in size the mutation appears as a sector 
of the fruit which differs in color, ripening season, or thick- 
ness of skin from the rest of the fruit. Such curious 
fruits have been called "spontaneous chimeras." These 
striped oranges and lemons are often found by the pickers, 
who usually incorrectly attribute the phenomena to the in- 
fluence of cross-pollination. When we consider that these 
mutations are always formed before pollination takes place, 
the inadequacy of the theory of pollen influence is evident. 

When mutation occurs at the base of the ovary it is not 
possible to continue it by propagation as no buds occur 
on the fruit. When, on the other hand, mutation occurs 
on the trunk or branches in a position where an adventi- 
tious bud may arise, then propagation is easy. 

As. before stated, many mutations showing various 
types of fruit and different bearing habits have occurred 
in the orchards, and through ignorant and careless cutting 
of bud-wood many of the worthless forms have become 
widely disseminated and now make up a considerable 
proportion of the trees in our commercial orchards. A 
vital need at the present time is a careful study of indi- 
vidual trees by each grower, who should determine which 
trees, if any, belong to unprofitable types and top-work 

1 H. Winkler, "Uber Propfbastarde und Pflanzliche Chi- 
maren," Ber. Deuts. Bot. Ges., 25: 568-576. E. Baur, "Propf- 
bastarde, Peri klinalchimaren und Hyperchimaren," loc. cit., 27 : 
603-605. 



124 



Citrus Fruits 



them to the most desirable types. In this way the aver- 
age cost of production may be greatly reduced. The 
great need for a study of the performance of individual 
citrus trees was emphasized by the writer in 1910. ] Since 
then many such studies have been made, by far the most 
comprehensive of which are those of A. D. Shamel. 2 Out 

of a mass of ma- 
terial the follow- 
ing condensed 
quotations have 
been selected 
from the studies 
of J. H. Norton, 3 
formerly Super- 
intendent of the 
Citrus Experi- 
ment Station at 
Riverside : 

"The Navel 

orange grove 

from which the 

following data 

are taken is located in West Highlands, San Bernardino 

County. The trees are the same age and the soil condi- 




Fig. 41. — Sectorial chimera of Valencia orange. 



1 Coit, J. Eliot, "The Relation of Asexual or Bud-Mutation to 
the Decadence of California Citrus Orchards," Rpt. 37th 
California Fruit Growers' Convention, 1910, p. 32. 

2 Shamel, A. D., "A Study of the Improvement of Citrus 
Fruits through Bud Selection," U. S. Dept. of Agriculture, 
Bureau Plant Industry, Circular No. 77, 1911. 

3 Norton, J. H., "Variations in the Productivity of Citrus 
Trees," California Cultivator, Vol. XL, No. 10, 1913. 



Improvement of Citrus Trees by Breeding 125 

tions uniform. This grove contains 1525 trees planted 
90 to the acre. The trees are about 16 years old and the 
grove is considered somewhat above the average in pro- 
ductiveness, yet the trees vary in yield from nothing to 
426 pounds of fruit per tree. 

" The following is the annual expense of this grove per 
tree: 

" General care including taxes, water, pruning, 

and fumigating, $1.14 

Interest on Investment, . 1.11 

Total annual expense per tree, $2.25 

" The fruit from this grove was sold for 1^ cents per 
pound on the tree. The trees that bore less than 150 
pounds of fruit were maintained at a loss, while those 
yielding more than 150 pounds paid a profit. This is 
graphically shown in Figure 44. 

" The curved line represents the yield per tree in pounds 
arranged in the order of yield. The horizontal line AB is 
the ' dead line,' and any tree the yield of which falls 
below this line was maintained at a loss. The shaded 
part of the curved line shows the trees that the owner 
realized no profits from. The shading above the line AB 
is due to the loss sustained by the trees recorded below 
the line. There were 490 trees or 32 per cent that yielded 
less than 150 pounds of fruit. This loss was made up by 
the profits from the next 646 trees, that is, the profit from 
42 per cent of this grove was required to offset the loss 
sustained by 32 per cent. Seventy-four per cent of this 
grove therefore gave neither profit nor loss. This leaves 



120 



Citrus Fruits 



the net income to be derived from 389 trees, or 26 per cent 
of the grove. 

" The total yield of the grove was 280,254.5 pounds of 




Fig. 42. — Orange showing sectorial chimera. From Ferrarius, 1646. 

oranges which at 1^ cents a pound, gave a gross in- 
come of $4203.81. The expense was $3431.25, leaving a 
net income of $772.56 or an average net profit per tree of 



Improvement of Citrus Trees by Breeding 127 

51 cents. Could the loss due to the 490 poor trees have 
been eliminated without increasing the production per 
tree, then the net profits from the remaining 1035 trees 
would have been $1125.96 or $1.09 per tree as compared 
with 51 cents profit per tree which was actually the case." 
The record of this West Highlands orange grove may be 
considered fairly typical of a large proportion of the 




Fig. 



43. — What is known as the "wrinkled sport" of Eureka lemon 
compared with normal fruit. Both from same tree. 



groves in California. The differences of yield noted were 
due both to fluctuations and mutations, but the extreme 
differences were undoubtedly due to mutations. The 
average yield would be greatly increased by top-working 
those of the 490 poor trees which proved to be mutative 
to buds carefully selected from the tree which yielded 
426 pounds. Many of the most progressive growers 
now keep accurate performance records and top-work 



128 Citrus Fruits 

the unprofitable trees as soon as they are discovered. 
In the case of the Australian and some other worthless 
mutations of Navel orange trees performance records are 
hardly necessary, as any experienced man should be able 
to recognize such poor types at a glance. For the segre- 
gation of trees which represent undesirable mutations, 
whose chief difference is that of yield, the performance 
record is indispensable. 

There is no scientific evidence to warrant the belief 
that anything worth while may be gained by the selection 
and propagation of trees whose high yield is due to fluctua- 
tion. It is vital that the high yield be due to a true muta- 
tion in order that the type may be propagated and progress 
made. As a matter of fact, the standard type of Wash- 
ington Navel is normally a heavy bearer and the majority 
of mutations observed are retrogressive. It is chiefly 
to counteract retrogression that top- working is practiced. 
Occasionally, however, mutations of peculiar value appear. 
The Thomson and the Navelencia may be cited as exam- 
ples. It is not unlikely that a general increase in the 
amount of individual tree study by many growers may 
lead to the discovery of new mutations which may be of 
great value to the industry. For him who brings such 
mutations to light is awaiting both honor and financial 
reward. 

THE SELECTION OF BUD-WOOD 

The foregoing discussion emphasizes the fact that the 
selection of bud-wood is an exceedingly important matter, 
for if one does everything else in the most approved way 























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130 Citrus Fruits 

yet does not have the kind of trees which bear good fruit, 
he will not have good fruit. This question is of far greater 
importance in connection with citrus fruits than with de- 
ciduous fruits, for it appears that oranges tend toward 
mutation much more generally than apples or peaches. 
On account of failure to select buds with due care in the 
past, a surprisingly large percentage of bearing orange 
trees are unprofitable. The average orchard is a mixture 
of different types, some good, some bad. Every planter 
should either grow his own trees, or select his own buds 
and have a nurseryman grow the trees on contract, or at 
least buy trees from a nurseryman who has a reputation 
for carefulness in the selection of bud-wood. 

It is of the very highest importance that all buds be cut 
from bearing trees while the fruit is on them and from trees 
which are known to have borne the ideal type of fruit 
on each and all of their branches for a series of years. It 
is a splendid plan to select certain typical mother trees in 
the orchard and keep an accurate record of the amount 
and quality of fruit produced. If off-type fruit is borne 
on any branch of a tree, no buds should ever be cut from 
that tree. In the case of the Navel orange, it happens 
that the best trees from which to cut buds present only 
fine fruiting brush which does not make satisfactory bud- 
wood. Such trees may be given a moderate pruning 
and thinning out over their whole tops and thus encour- 
aged to produce plump twigs, more suitable for bud- 
wood, the following season. 

In these days there is much talk about " pedigreed " 
nursery stock. Usually what is sold as pedigreed stock 
is stock whose scions are said to have been cut from 



Improvement of Citrus Trees by Breeding 131 

a tree or trees which are said to have yielded exceptionally 
well. This is good as far as it goes, but it does not fully 
protect the buyer from ignorant or careless dealers. The 
unit of the plant is not the tree ; it is the cell. The term 
" pedigree " may properly be referred to animals, not to 
plants. Our greatest source of mixed and worthless stock 
is the irresponsible amateur propagators who have been 
operating so extensively on vacant city lots and in yards 
and gardens since the price of trees has been high. Many 
of the trees produced in this way are beautifully grown 
specimens, but the buyer should beware of them unless 
he can satisfy himself by personal investigation that the 
buds have been properly selected. 



CHAPTER VIII 
JUDGING CITRUS FRUITS 

A great many different scales have been proposed 
from time to time for the judging of citrus fruits. In 
1892 the Florida Horticultural Society adopted an official 
scale together with rules and regulations.. In 1894 the 
Executive Committee of the Los Angeles Chamber of 
Commerce adopted an official scale for California. 

These scales, while most excellent as ideals toward 
which to work, are but little used in citrus exhibitions for 
the reason that their use requires too much time. The 
judges are usually expected to judge hundreds of exhibits, 
sometimes aggregating twenty or more carloads of fruit, 
in twelve or fifteen hours. Obviously it is possible to use 
the score-card only in those classes where competition is 
very close, and in such cases the great value of the score- 
card with a fixed scale is clearly evident. 

The Florida rules require seven specimens to constitute 
a plate entitled to entry. In California five specimens 
are required. 

Interest in citrus judging has been greatly stimulated, 
in California, by the inauguration in 1911 of the National 
Orange Show, which is held annually at San Bernardino, 
and represents, for the Southwest at least, the citrus event 
of the year. 

132 



Judging Citrus Fruits 133 



Orange Score-card 

Size (uniformity) 5 

Form (typiealness) 15 

Stem 5 

Size 3 

Color 2 

Rind 35 

Color 10 

Texture 5 

Thickness 5 

Freedom from blemishes 15 
Navel or seeds 5 

Size 3 

Shape 1 

Prominence 1 

Juice 30 

Abundance 10 

Color 5 

Flavor 15 

Rag 5 

Amount 3 

Character 2 

Total 100 



ORANGE STANDARDS 

Size. — Oranges for exhibit may be of any size from small, 
250's, to large, 126's. The most desirable size is medium, 
176's, which are 2yf inches in diameter. Sizing should be 
accurate, one-half unit discount for each specimen varying 
| inch from the size. 

Form.. — Fruit must have shape typical of variety and be 
free from creases or corrugations. 

Stein. — Stem must be small, but close and square, level 
with surface of rind, sepals green and plump. For each 
missing stem deduct one point. 

Rind. — Color must be deep orange, the darker the better. 
Bloom must be perceptible ; texture smooth and fine with 



134 Citrus Fruits 

kid-glove finish ; thickness f to f\ inch. In discounting for 
thick rind consideration should be given to the length of 
time fruit has been picked, as rind gradually decreases in 
thickness. Fruit must be free from blemishes such as 
insect injuries, decay, wind scars, or abrasions. 

Navel or seeds. — Navel marks to be of good form -and 
from \ to \ inch in diameter. The perfect orange should 
be seedless ; discount for more than normal number of seeds 
for variety. 

Juice. — The largest possible amount of juice is desirable. 
The perfect orange should sink in water. If fruit floats, 
discount according to degree of buoyancy. Color should 
be pale orange except in case of blood oranges, which should 
have deep red juice. Flavor should be fine, acid and sugar 
well blended, and otherwise characteristic of variety. 

Rag. — The less rag the better. Character should be deli- 
cate and melting. 

Lemon Score-card 

Size (uniformity) 5 

Form (typiealness) 15 

Stem 5 

Size 3 

Color 2 

Rind 35 

Color 5 

Texture 5 

Thickness 5 

Freedom from bitterness 5 

Freedom from blemishes 15 

Seeds (absence) 5 

Juice 30 

Abundance .... 15 

Color 5 

Flavor 10 

Rag 5 

Amount 3 

Character ..... 2 

Total 100 



Judging Citrus Fruits 135 



LEMON STANDARDS 

Size. — Lemons may be exhibited in any size from large, 
250's, to small, 360's. The most desirable size is the 300, 
which is 2| inches in diameter. Sizing should be accurate. 
One-half unit discount for each specimen varying § inch from 
standard. 

Form. — Fruit must have shape typical of variety and be 
free from irregularities. Sunburned lemons are inequilateral 
and should be heavily discounted. 

Stem. — Stem must be present, cut close and square, 
sepals green and plump. For each missing stem deduct one 
point. 

Rind. — Color must be pale or whitish yellow ; discount 
for bronze tints, green marks, or sunburn. Bloom should be 
perceptible ; texture smooth and fine with waxlike finish ; 
strong and elastic with uninjured oil cells. Thickness should 
be from ■$$ to y\ inch. Allowance for thick rind should be 
made for fresh lemons when exhibited. Just how much 
allowance should be made will depend of course on the 
amount of curing the lemons have undergone, and this is 
often difficult of determination by any except experienced 
persons. Fruit must be free from all blemishes. 

Seeds. — The perfect lemon is seedless. Discount f point 
for each seed. 

Juice. — The largest possible amount of juice is desirable. 
Specific gravity should be 1 (equal to that of water), with 
buoyancy of § oz. allowed to large sizes and \ oz. to medium 
and small sizes without discount. Color should be pale 
lemon yellow. Flavor must be clear and fine. Discount 
heavily for bitterness of rind. 

Rag. — The less rag the better ; character should be delicate 
and tender. 



136 Citrus Fruits 

Pomelo Score-card 

Size (uniformity) 5 

Form (typicalness) 10 

Stem 5 

Color 2 

Location 1 

Size 2 

Rind 35 

Color 5 

Texture 5 

Thickness 10 

Smoothness .... 5 

Freedom from blemishes 10 

Seeds (number) 10 

Juice 25 

Abundance 10 

Color 5 

Flavor 10 

Rag (tenderness) 10 

Total 100 

POMELO STANDARDS 

Size. — Pomelos may be exhibited in any size from large, 
28's, to small, 96's. The most desirable size is the 54, in which 
the fruits are A\ inches in diameter. Sizing should be 
accurate. One-half unit discount for each fruit varying 
\ inch from standard. 

Form. — Fruit must have shape typical of variety and be 
free from irregularities. 

Stem. — Stem must be present, cut close and square, sepals 
green and plump. For each missing stem deduct one point. 

Rind. — The color should be ivory white, the texture 
smooth and fine. Thickness should be \ to T \ inch. Fruit 
must be free from all blemishes. 

Seeds. — Seedlessness is the standard for pomelos. Cut 
\ point for each average seed per fruit. 



Judging Citrus Fruits 137 

Juice. — The largest possible amount of juice is desirable. 
When placed in water the fruit should not rise more than 
| inch above the water. Flavor must be characteristic of 
the variety with acidity and sweetness well blended. 

Rag. — Rag should be tender enough to cut easily with a 
spoon. 

Score-card for Packed Boxes 

Exterior appearance 40 

Cleanliness 10 

Neatness 5 

Artistic quality of label 10 

Size and placing ... 10 

Stenciling 5 

Nailing 20 

Position of cover ... 5 

Position of cleats ... 5 

Placing of nails ... 5 

Placing of strap ... 5 
Wrapping 20 

Quality of paper ... 7 

Artistic quality of design 7 

Twist 6 

Placing ■. . 20 

Facing 5 

Alignment 5 

Firmness 5 

Crown 5 

Total 100 



STANDARDS FOR PACKED BOXES 

Appearance. — Box material must be perfectly bright and 
clean and put together in a neat manner. The lithograph 
label must have artistic color qualities ; it should be of original 
design, and the illustrations should be true to life. Box 
labels should be exactly 10 X 11 inches for oranges and 
10 X 13 inches for lemons, including a | inch border in each 



138 Citrus Fruits 

case. Combination labels are to be discounted. Labels 
should be placed flush with bottom of box, leaving space 
at top for stamping. This strip of bare wood should show 
the impressions of three rubber stamps as follows : in the 
right-hand corner, the number of fruit in the box ; in the 
center, the variety of oranges or pomelos, and in the left- 
hand corner, the number of the packer. The name of the 
variety of lemons is not placed on the box for reasons ex- 
plained in Chapter XVI. 

Nailing. — The cover pieces must be perfectly parallel 
and the cleats must be above the cover. Cleats below 
the cover should debar the box from exhibit. Nails must 
be properly placed and driven home without showing print 
of hammer in wood. 

Wrapping. — Paper should be strong and of good quality. 
Design should be artistic, and the twist should be carefully 
made. 

Placing. — On placing fruit in the boxes the design on the 
wrapping paper should be made to face the openings in the 
side of the box. The alignment should be as nearly perfect 
as possible. Fruit should be firmly placed and the standard 
amount of crown is 1 inch at center. 

Score Card for Feature Exhibits 

Quantity and quality of fruit .... 50 

Artistic qualities of plant decoration . 15 

Bunting and electric effects .... 15 

Originality of design . 10 

Unity of expression ....... 10 

Total 100 



CHAPTER IX 

SELECTION OF SITE AND PREPARATION 
FOR PLANTING 

Success with citrus fruits depends to a very large ex- 
tent upon the proper selection of the site for the orchard. 
This is especially true in countries where the climatic and 
soil conditions vary widely in the same locality. It is 
poor policy to examine a piece of land or a bearing 
orchard without a program. This is especially true when 
different propositions are to be contrasted with a view to 
deciding on a purchase. 

It is suggested that the following list of points be noted 
in going over every piece of land. Each point may be 
weighted after the fashion of a score-card and thus accu- 
rate comparisons between the different properties exam- 
ined made easier. 

PROPOSED SCORE-CARD FOR CITRUS LANDS 

1. Price per acre. 

2. Freedom from frost. 
Legal right. 



3. Water 



Amount. 
Quality. 
Cost. 

139 



140 Citrus Fruits 

4. Continuity of tract. 

5. Quality and kind of soil. 

6. Drainage outlet. 

7. Freedom from hardpan. 

8. Freedom from stones and brush. 

9. Freedom from alkali. 

10. Freedom from waste land. 

11. Susceptibility to wind. 

12. Nearness to town. 

13. Nearness to packing-houses. 

14. Quality of roads. 

15. Distance from scale infested orchard. 

Additional Points for Bearing Orchards 

16. Freedom from scale and diseases. 

17. Freedom from mottled-leaf. 

18. Uniformity of trees and record of yield. 

19. Condition of trees as to pruning. 

20. Adaptation of variety to district. 

THE FROST QUESTION 

One of the most important factors limiting the growth of 
citrus fruits is frost. The frost hazard of any given piece 
of land is at best a very uncertain quantity and may be 
judged only approximately even after years of experience 
and observation. Within the established citrus districts, 
as a rule, the elevated slopes of the foothills, preferably 
with a southern or western exposure, at an elevation of 
from 500 to 1500 feet above sea level and 100 to 500 feet 
or more above the bottom or " draw" of the valley, are 
the most frost-free locations. On lands subject to heavy 



Selection of Site and Preparation for Planting 141 

frosts every year, the expense of orchard heating would be 
too great. Usually the heavy cold air flows down and col- 
lects in the valleys, leaving the higher lands above the 
frost line. There are notable exceptions to this general 
rule, however, for when the drop in temperature is ac- 
companied by strong winds, as was the case during the 
blizzard of January, 1913, the high and supposedly frost 
free land may suffer most of all. Such blizzards are 
fortunately of extremely rare occurrence. 

The frost hazard of any given piece of land (except that 
which is closely surrounded by old citrus groves) can 
only be found by exposing self-registering thermometers 
for several winters. If there are homesteads with yards 
and gardens in the vicinity, a study of the flowering plants 
may give some idea of the frost hazard. For example, 
if old and well established plants of bougainvillaea, Sola- 
rium wenlandii, poinsettia, or jacaranda are found which 
show no signs of having been killed back, it is fairly certain 
that a lemon orchard in the immediate vicinity would not 
be injured except perhaps in occasional and exceptional 
years. 

THE WATER SUPPLY 

In no citrus district of California is the rainfall sufficient 
for irrigation. The amount of water needed under different 
conditions will be discussed in Chapter XII, but it may be 
well to point out here that it behooves the buyer of citrus 
land or orchards to make a careful study of the character 
of the water supply. He should bear in mind that upon 
the water supply depends the life of the trees and that he 
should thoroughly understand the system of which his 



142 Citrm Fruits- 

ranch is a part. Water rights in an irrigated country are 
often complicated and one should familiarize himself not 
only with the legal details, but with the present physical 
condition of the entire system. 

In localities in which the water is pumped from wells 
located in the groves it is not uncommon for the gradual 
increase in use of water, which takes place as the planting 
in the neighborhood increases, to lower the water table to 
such an extent that the old wells have to be dug deeper 
and pumps of higher power installed. The indications 
are that as the industry grows and the value of water 
increases the number of law-suits will increase rather than 
diminish. The best water right is a share in an old and 
well established canal company which holds prior rights 
and draws its supply from the melting snows on the 
mountains, and which guarantees the delivery of a certain 
number of miner's inches per month per share. 

SOIL ADAPTATIONS 

California soils are famed for their great depth and 
fertility, and the soils of the citrus belt are no exception 
to the rule. There is a wonderful variation, however, 
in the kinds of soil now occupied by citrus groves. 

We have the fine sandy soil of Anaheim, the bluish 
muck soils of Santa Paula, the black adobe of La Habra, 
the gravelly loam of Upland, the disintegrated granite 
of Riverside, the red loam of Redlands, the dry-bog of 
Porterville, the red adobe of Fairoaks, and the soft desert 
soils of Imperial. Citrus trees are now growing success- 
fully in all of these soils and do not seem to be particularly 



Selection of Site and Preparation for Planting 143 

partial to any one kind so long as the physical conditions 
are good. Of course it is easier as well as cheaper to culti- 
vate a soft sandy loam than a sticky adobe, and easily 
worked soils are much more desirable from the standpoint 
of the man who is to till them. 

What are these conditions then which make for success 
or failure and are more important than the type of the soil ? 
In the first place, nothing is more fatal to success than to 
judge the value of a piece of ground by the nature of the 
surface soil. By digging or boring down to a depth of a 
few inches or feet, something entirely different from that 
seen on top may be encountered, which would doom the 
proposed planting to eventual failure. 

It is not uncommon to find subsoils so hard that it is 
impossible for water and tree roots to penetrate them. On 
such soils trees are greatly restricted in their root develop- 
ment and the reservoir for water is much reduced. Such 
soils are apt to be too wet in the rainy season and are very 
difficult to irrigate properly. 

On the other hand, the subsoil may be too coarse and 
open, unretentive of moisture, and deficient in plant food. 
Both heavy and light soils have advantages peculiar to 
themselves and a compromise between them, usually known 
as sandy loam, is nearly always the most desirable. 

To sum up, then, the soil for a citrus orchard may be 
of any type, preferably a sandy loam ; but it must be at 
least four or five feet deep ; it must be free from hardpan 
or strata of coarse gravel ; it must be well drained ; and it 
should be so situated as to make irrigation easy. In some 
cases a thin stratum of hardpan a foot or two below the 
surface may be broken up with dynamite before the trees 



144 Citrus Fruits 

are planted. This allows the roots and the water to get 
through and may sometimes make otherwise undesirable 
land available for citrus trees. 

Of the two most common conditions, a light surface 
soil over heavy clay subsoil is more to be desired than a 
heavy clay surface soil over sand or gravel. 

The ideal soil is a rich, nearly level, friable, easily worked 
loam, eight or more feet deep, growing gradually lighter as 
the depth increases. This not only provides a great store- 
house of plant food, but a great reservoir to hold water. 

Alkali soils commonly occur on the floors of the valleys 
where it is usually too frosty for citrus trees. Occa- 
sionally, however, the question arises as to the suscepti- 
bility of citrus trees to alkali. Where the soil contains 
two-tenths of one per cent of total salts, the trees are 
likely to be injuriously affected. A total salt content 
of less than one-tenth of one per cent is usually con- 
sidered safe. These figures will be found to vary some, 
however, according to the proportions of the different 
salts which taken together are known as "alkali," some of 
which (such as sodium carbonate) are much more injurious 
than others. 

So-called acid soils are very rare in the citrus districts of 
the West. They are more apt to occur in wet, swampy 
land, or in recently cleared forest soil, where there is a 
large amount of vegetable matter in the ground. Such a 
condition can be definitely determined by chemical 
analysis. Soil acidity is easily corrected by an application 
of lime. 

The question of the disposition of waste water is an im- 
portant one, as in many places there are stringent laws 



Selection of Site and Preparation for Planting 145 

against allowing it to flow into the roads or on to a neigh- 
bor's land. Theoretically there should be no waste water, 
as it should all be used on the land. In many cases, 
however, and especially on clay soil and with careless 
laborers, a certain amount of water will escape from the 
lower ends of the furrows and it may become necessary to 
dig a long ditch or even put in a very expensive pipe line 
to dispose of this waste water. 

The question of insect pests should also be considered. 
A location far from any scale-infested orchard may mean 
that fumigation may not be necessary for many years, 
if at all, whereas a site on the windward side of a badly 
infested orchard will mean fumigation almost from the 
first, with all the attendant bother and expense. 

Not the least important point to consider is the nearness 
to the railroad and packing-house, and the condition of 
the roads over which the fruit must be hauled. The labor 
problem also is important. Orchards near small towns 
have the advantage of a larger and more dependable labor 
supply, and this is quite an advantage at picking time and 
especially when frost fighting becomes necessary. 

Clearing any leveling. — For reasons pointed out in Chap- 
ter XXI, it is very important in clearing land for citrus 
trees to dig the old trees out by the roots, being careful 
to get out all the large roots to a depth of several feet. 
Especially is this true where oak or sycamore trees have 
occupied the land, for the roots of these trees are especially 
apt to harbor the Armellaria fungus for many years. 

On account of the high price of well located citrus land, 
it has become profitable to develop very stony ground. All 
the stones above the size of an orange are hauled out and 



146 Citrus Fruits 

built into walls or used in road construction. The land 
is then deeply plowed and the stones picked up again, this 
process being continued till all the stones are removed to a 
depth of ten or twelve inches. A good deal of such land 
proves very fertile and produces high class fruit. 

After the land is cleared, it must be leveled with 
" Fresno " or other scrapers until the surface presents a 
uniform grade. This is very important, for otherwise 
the irrigation water will run through different parts of the 
rows at different rates of speed, and consequently sink to 
unequal depths, with the result that some trees get too 
much water while others do not get enough. On spots 
where hardpan is encountered, especially on knolls from 
which the soil is removed to fill up depressions, the condi- 
tions may be greatly improved by blasting and breaking 
up the hardpan in order that the water and roots may get 
through. The cost of blasting will vary with the thick- 
ness and depth of the hardpan. For instance, when a 
stratum six inches thick lies four feet below the surface, 
it will require two sticks or one pound of 25 per cent dyna- 
mite, four feet of fuse, and a cap. The cost of materials 
and labor will amount to about 25 cents per tree, the 
charges being placed only where the trees are to stand. If 
the ground is quite dry, as it should be, when the work is 
done the shattering effect will extend for about five feet 
in all directions. The chunks of hardpan which are 
loosened should be removed from the holes before the trees 
are planted. 



CHAPTER X 

PLANTING THE ORCHARD 

After the ground has been properly leveled, it should 
be put in the best of tilth by deep plowing and cultivat- 
ing. It is a good plan to plow deeply in the fall and leave 
the land rough during the rains of winter. In spring, 
the volunteer crop of weeds and grass may be turned 
under and the land harrowed and dragged. This will 
leave the land smooth and in excellent condition for 
staking out the orchard. 

ORCHARD PLANS 

There are three objects to be considered in laying out 
the orchard : symmetry of appearance, economy of space, 
and facility for future care. On level land, of course, the 
first step is to set the trees in straight rows and at equal 
distances apart. There are various methods of disposing 
of the straight row, however, and these methods all have 
their advocates, and each one its advantages. The most 
important of these are the triangular, square, hexagonal, 
and quincunx. 

In the triangular system, the trees are set in rows but 
the first tree in every second row is set not on the line 
but is moved in half the distance between trees. By this 

147 



148 Citrus Fruits 

method more room is given the trees and a less number 
is planted to the acre than by the square method, but 
it is possible to cultivate and even irrigate three ways 
through the orchard. In laying out the orchard, the 
ground is first laid out in squares, after which a line is run 
diagonally across the field and a tree stake placed wherever 
this line passes through the corners or cuts the side of a 
square. 

The square system is by far the most commonly used, 
and may be followed either for squares or oblong rectangles. 
The rows of trees intersect each other at right angles and 
cultivation may be carried on in two directions. 

By the hexagonal system, the trees are set equidistant 
from each other. Six trees form a hexagon with a seventh 
in the center. By this means the ground is more eco- 
nomically divided and more trees are planted per acre 
at a given distance apart than by any other method. 

By the quincunx system four trees constitute a square 
with a fifth in the center, thus doubling the number of 
rows. This method is chiefly used in planting with the 
idea of removing the center trees, which are usually of 
dwarf varieties, when those designed to be permanent 
shall have attained a considerable size. The orchard 
then assumes the square plan. 

The quincunx system is rarely used in planting citrus 
orchards as it is not customary to use other and smaller 
varieties of fruit trees as temporary fillers in citrus or- 
chards. 

The following table gives the number of trees required 
to plant an acre at various distances apart according to 
each of the above four plans : 



Planting the Orchard 



149 



Number op Trees to the Acre 1 



Distance Apart 


Quincunx 


Hexagonal 


Square 


Triangular 


35 x 35 feet 


65 


41 


36 


33 


30 x 30 feet 


83 


55 


48 


44 


25 x 25 feet 


126 


81 


70 


64 


25 x 20 feet 






87 


79 


24 x 24 feet 


137 


86 


76 




22 x 22 feet 


173 


103 


90 




20 X 20 feet 


199 . 


126 


108 


98 


18 x 18 feet 


247 


142 


134 


122 


20 x 15 feet 






145 


132 



There is a good deal of variation throughout California 
in regard to the distances at which citrus trees are planted. 
The following are the usual distances which give the best 
results : kumquats, 12 X 12 feet ; tangerines, 20 X 20 
feet ; Navel oranges, 22 X 22 feet ; and Valencia oranges, 
lemons, and pomelos, 24 X 24 feet. Lemons sometimes 
bear well and produce a larger tonnage per acre when 
planted close in one direction. The old Eureka orchard 
at the Limoneira Ranch near Santa Paula, which is planted 
26 X 15 feet, is a notable example of this. 

Many citrus growers prefer to employ a surveyor to 
lay out the orchard and set the stakes which mark the 
points where the trees are to stand. While this is a good 
plan with large plantings, especially where the ground is 
rolling, it is not necessary in the case of five or ten acre 
blocks. A satisfactory way to lay out a small tract is by 
means of a strong wire as long as the tract is wide. This 

1 Adapted from Hume, Bailey, and Wickson. 



150 Citrus Fruits 

should be carefully measured and a button soldered to 
the wire for each tree row. After the stakes are set along 
each side of the field marking the rows, the wire may be 
stretched between each pair and thus carried across the 
field, a stake being set at every point to be occupied by a 
tree. 

Much of the land available for citrus planting is entirely 
too steep and broken to admit of any of the plans above 
mentioned. Such lands are often of great value on ac- 
count of their freedom from frost. In such cases the rows 
are laid off on contours. By this means the irrigation 
furrows are run on a more uniform grade throughout their 
length, and the storm water problem is solved, since the 
water which accumulates in each row will be carried off 
separately to the side of the field and safely disposed of. 

Where the general slope of the land is not more than 
15 per cent, cultivation may be carried on at right angles 
to the irrigation furrows after a slight ridge has been 
established in the tree row. In order to facilitate orchard 
operations it is wise to arrange the trees in rows running 
up and down the hill. 

On very steep hillsides it is necessary to build terraces 
and in such cases the trees are planted on the brink and 
cultivation and irrigation is limited to one side of the 
tree row. The terrace banks should be planted with 
some hardy plant which will displace weeds and prevent 
washing. In coast counties where the air is moist Mesem- 
bryanthemum australis (white flowered) or M. roseum 
(pink flowered) are recommended. In interior valleys 
perhaps Lippia may be used for this purpose. 

Irrigation water is usually conducted in a pipe line 



Planting the Orchard 151 

along the crest of a ridge with contours or terraces diverg- 
ing on either side at irregular intervals. Where the con- 
tours converge to within less than twenty feet the trees 
are omitted. 

Contours may be easily laid out by the use of a twenty- 
five foot plank to which a carpenter's spirit-level is 
attached. One end is equipped with an adjustable leg 
or shoe upon which is marked off a scale to hundredths 
of a foot. By adjusting the length of the leg for the 
desired grade and pivoting on the other end, the shoe 
can be located on the next point of the grade by trial, 
the main plank being kept level as determined by the 
spirit-level. The grade established will depend a good 
deal upon the character of the soil and the nature of the 
slope, inasmuch as some soils tend to wash much more 
easily than others. 

Time of planting. — As explained in a previous chapter, 
citrus trees have three more or less distinct periods of 
growth during the year. It is not wise to transplant the 
trees during one of these periods of growth. They may 
be planted at any time of year, but should be as nearly 
dormant as possible. The most convenient as well as 
the customary time of planting in California is between 
April 1 and June 15, preferably during the month of May 
or just after completion of the first growth and before 
the starting of the second. 

KOOT-STOCKS 

While there are at least seven possible root-stocks upon 
which citrus trees may be grown, there are only three which 



152 Citrus Fruits 

are used commercially in California at the present time, 
viz. : the sour or bitter, the sweet, and the pomelo. It is 
said that at present, practically every citrus tree in 
Europe is grown on the sour-stock. Perhaps we would 
be safe in saying that every tree in California would be 
as well off on sour-stock, yet there are a few people who 
still claim that, in certain situations, sweet-stock is best, 
at least for oranges. All lemons should be grown on sour- 
stock on account of its great resistance to brown-rot 
gumming. Sour-stock should be used for oranges and 
pomelos on low, heavy, or wet soils. On high, dry, well- 
drained soil sweet-stock is practically as good but ap- 
parently no better for oranges. Orange trees will make 
a quicker start into growth and begin to bear fruit a little 
earlier on sweet-stock, but after the trees are six or seven 
years old no one can tell any difference in the size or 
fruitfulness of the trees. The sour-stock has the advan- 
tage, therefore, in being more resistant to gum diseases 
and foot-rot of various kinds. 

The use of pomelo stock is increasing somewhat, although 
it has not been widely experimented with. It is giving 
pronounced success where used for lemons on open 
gravelly soils in the interior valleys. Pomelo seedlings 
often give trouble in the seed-bed by gumming and by 
their peculiar habit of blooming and setting fruit when 
they are only two or three inches high. 

In addition to the above three stocks there are several 
others which are entitled to mention for the reason that 
while they may be no longer used in propagation they 
are often met with in old orchards. The rough lemon is 
said to be hardy and to a certain extent drought-resistant, 



Planting the Orchard 



153 



and is being experimented with. It will probably not 
gain favor, however, as it is very susceptible to brown-rot 
gumming. 

Trifoliate stock is largely used in Florida, and in the 
citrus districts of Louisiana and Texas it is used almost 
exclusively for growing the Satsuma orange, which does 
very well on this stock. In California, however, trifoliate 
is but little used. There remain a few old orange and 




Fig. 45. — Cowpeas as an intercrop in young lemon orchard. 

pomelo orchards upon it which are doing fairly well, but 
failures are more frequent than successes, and in very few 
cases does it appear to show any advantage over the sour 
or sweet. In some places Navel oranges sweeten earlier 
in the fall when grown on trifoliate stock. Perhaps the 
trifoliate comes nearest being a success when used on 
heavy soil in the Tulare district. Trifoliate is very ob- 
jectionable for lemon trees and has been an absolute failure 
in every case recorded in California. 



154 Citrus Fruits 

Chinese lemon, a form of citron, was once used to some 
extent but has long been abandoned entirely. It forced 
the tree into an extremely rapid growth which resulted 
in coarse fruit. It was short lived and quite susceptible 
to various root decays. 

Ordinary lemon stock was sometimes used in the early 
days. Instead of growing seedlings and budding upon 
them, some of the early planters simply rooted cuttings 
of the variety desired and set them out in the orchard. A 
few of these old trees remain, but their record does not 
furnish a good recommendation for this stock, as the 
trees are nearly always more or less affected with root-rot. 
But aside from root-rot lemon roots have clearly shown 
their inferiority. The bud unions of certain lemon trees 
at the Limoneira Ranch became buried with soil and 
one or two roots put out from above the bud. Such trees 
showed a distinct depreciation in the amount and quality 
of fruit and vigor of foliage. Where only one large lemon 
root put out, the tree shows the effects on that side only, 
and this was the case even when the lemon root was ap- 
parently healthy and vigorous. 

The question is sometimes asked as to whether the 
fruit of the orange will be deleteriously affected by the sap 
passing through a section of lemon wood as is the case 
when budded lemon trees are top-worked to oranges. A 
large number of instances of this have been reported on, 
and in no case does there seem to be any injury or reduc- 
tion in quality of the oranges from having grown on lemon 
trunks. 

Oranges are never grown from cuttings for the reason 
that orange cuttings cannot be induced to strike root. 



Planting the Orchard 155 

There has been much difference of opinion and dis- 
cussion of the point as to whether or not the hardiness of 
a cold resisting stock, such as the trifoliate, was trans- 
mitted to the scion. Published reports x indicate that 
such has been the case in Florida. In California such an 
effect, if present at all, is so slight as to be hardly worth 
recording. Rows of several varieties of trees on each of 
the different stocks have been grown for years at the 
Citrus Experiment Station at Riverside and have passed 
through two periods of excessive cold. After a very 
critical examination of the trees, the writer was forced to 
the conclusion that, in this case at least, there was prac- 
tically no difference in the amount of injury from cold 
sustained bv. the trees on the different stocks. 



DIGGING THE HOLES 

Before the holes are dug, the notched planting-board 
should always be used in order to be able to set the tree 
in the hole in the exact position previously occupied by 
the stake. Large holes should be dug, two feet wide and 
one and a half feet deep. The bottom of the hole should 
be carefully inspected for stone or hardpan and should 
be well loosened up either with the spade or with a charge 
of explosive. If the trees come with bare roots, they 
should be handled with extreme care to prevent drying 
out. 

It is customary to puddle the roots of trees when they 
are not balled. This puddling is done at the nursery and 

1 G. L. Taber, Florida Farmer and Fruit-Grower, 1901. 



156 



Citrus Fruits 



decreases to a small extent the susceptibility to injury 
from drying while handling in the field. The roots should 
be trimmed, all broken ends being cut off smooth, and the 
soil sifted in around the roots so as to leave no air holes. 

This soil should 
be moist and fine 
and must always 
be well tramped 
in order to bring 
the roots in firm 
contact with it. 
It is very impor- 
tant to set the 
trees at precisely 
the same height 
that they were 
in the nursery. 
After settling, 
citrus trees 
should always 
stand in the or- 
chard at the same 
height that they 
did in the nurs- 
ery. A citrus 
tree planted too 
deep or with the soil above the bud is doomed to 
failure. 

When using the notched planting-board some planters 
prefer to set the guide pegs for several rows before the 
holes are dug, keeping the board at right angles to the 




Fig. 46. — Breaking a layer of hardpan by 
means of a stick of dynamite discharged in 
each tree hole. 



Planting the Orchard 157 

tree row. A deep furrow is then plowed half way between 
the two rows of pegs. The holes are then dug in this 
furrow and after the trees are planted the water may be 
turned into the furrow. It is necessary of course to draw 
up a small mound of soil immediately about the tree to 
prevent the water from coming in contact with the bark. 

When balled stock is planted, it is customary to allow 
the balls and sacking to remain. The strings are cut 
from about the crown and the tree planted, sack and all. 
It is also advisable to slit the sack at the bottom in order 
to allow irrigation water to enter more easily. Ordinary 
sacking decays in two months and the roots are not 
interfered with. In the case of the balls being composed 
of very stiff adobe soil, especially when planted in loose 
sandy soil, they should be soaked in water and loosened 
somewhat before planting. It is not advisable to attempt 
to stimulate the trees by putting fertilizer in the holes. 
Fertilizer may injure or even kill bare-rooted trees unless 
it is very thoroughly incorporated with the soil before the 
trees are planted. 

Bare-rooted trees should be cut back when planted, 
the cut waxed over, and an entirely new head allowed to 
form. Balled trees may retain short stubs representing 
the main branches of the head, and a few leaves. Sun 
protectors are necessary to prevent sunburning of the 
trunk and should always be used, especially in hot interior 
valleys. Sun protectors may be made out of old sacking 
wrapped around the trunk or especially manufactured 
yucca tree protectors may be used. A number of thick- 
nesses of old newspapers wrapped loosely around the 
trunk and tied with a string answers verv well and has the 



158 



Citrus Fruits 



advantage over yucca of being cheap as well as adjustable 
in length. Such tree protectors should be taken off 
once or twice during the first year in order to remove the 
water-sprouts from the trunk. 

After the tree is well set and 
thoroughly tramped in, it 
should be watered immediately, 
the ground being thoroughly 
soaked. In order to save time, 
orchards are sometimes planted 
before the facilities for irrigat- 
ing are completed. In this case 
the trees must be "tanked" or 
watered from a tank wagon. 
A basin is excavated about 
each tree, the soil being drawn 
against the trunk in the center 
to protect it from the water. 
After these basins are filled 
once or twice, the loose dry 
soil is returned to its place, in 
order to conserve the moisture, 
and the ground leveled off. If 
well attended to, tanked trees 
grow fully as well as those 
irrigated in the ordinary way. 
Whether they may be tanked to advantage the second 
year will depend on the cost of hauling the water. Usually 
the permanent system of irrigation should be ready by 
the second summer. 

Wherever citrus trees are planted in new localities, 




Fig. 47. — Newly set tree prop 
erly protected from the sun. 



Planting the Orchard 159 

where grain farming, rather than irrigated crops, have 
been the rule, a sharp lookout must be kept for ground 
squirrels and gophers. Both of these pestiferous rodents 
are apt to cause serious injury to newly planted citrus 
trees unless effectually prevented. Detailed directions 
for fighting gophers and ground squirrels are given in 
Chapter XXIV. 

INTERCROPPING 

The question often arises as to the advisability of grow- 
ing intercalary crops between the trees in order to gain 
some revenue from the land while waiting for the trees to 
come into bearing. There are many cases where this 
has been done advantageously, although the intercropped 
citrus orchard is the exception rather than the rule. 
Such a practice is permissible only when the intercrop 
does not interfere with the best growth of the citrus trees. 
Citrus nursery stock is often grown between the rows of a 
young orchard where the soil is sandy and does not pack 
and bake as a result of the digging and tramping incident 
to balling the nursery trees. Vegetables, such as toma- 
toes, potatoes, peppers, lima beans, or black-eyed peas, 
may be grown to advantage. In interior valleys kaffir- 
corn and stock-beets make a satisfactory crop which may 
be used for hog feed. The corn-stalks are often con- 
venient for wrapping the young trees in winter. A strip 
of alfalfa down the middles improves the soil, especially 
when the hay is cut and applied to the cultivated strip of 
land on either side of the tree rows. Such a strip of 
alfalfa should be reduced in width from year to year and 
plowed out entirely by the fifth year. Strawberries are 



'160 Citrus Fruits 

very injurious to citrus orchards, especially on heavy soils, 
as they require such frequent irrigations that great injury 
from gum disease often results. In any event the young 
orchard should never be rented to tenant farmers to get 
all they can out of the land without reference to the good 
of the trees. 

THE COST OF PLANTING 

It is very difficult to estimate the cost of bringing a 
citrus orchard to bearing on account of the very great 
variation in existing conditions. Tait 1 gives an average 
estimate for a ten acre orange orchard in the Pomona 
district which gives a fair idea of the costs* for the first 
five years. 

Cost of Planting and Caring for Ten Acre Orange 
Orchard for Five Years 

Ten acres of orange land $1500 

Water right, or stock in Water Co 1300 

Preparing and grading land 200 

1000 trees at $1 each 1000 

Planting trees at 7\ cts. each 75 

Irrigating system 175 

Irrigation and cultivation, five years 1500 

Taxes and incidentals, five years 250 

Fertilizer, three years 250 

Total for 10 acres, 5 years $6250 

Since 1911 the cost of some items has increased, espe- 
cially clearing and grading, as the land still available in 
this district is often encumbered with bowlders and brush. 
The cost of water has also increased. See page 359. 

1 C. E. Tait — " U. S. D. A., Office of Exp. Stations," Bull. 
236, 1911. 



Planting the Orchard 161 

Cost of New Planting, 1911, by San Diego Fruit Co. 1 



Orchard 
No.— 


Acres 


Num- 
ber of 
Trees 


Cost 


Sur- 
vey 


Water 


Labor 


Fer- 
tilizer 


Total 


9 . . . . 


2| 


158 


$126.05 


$5.00 


$8.75 


$16.21 


$5.62 


$161.63 


31 . 






2i 


237 


177.60 


5.00 


8.75 


34.21 


9.37 


234.93 


32 . 






M 


351 


278.25 


10.00 


15.75 


58.90 


13.12 


376.02 


33 . 






6 


491 


370.72 


35.00 


21.00 


133.57 


18.75 


579.04 


78 . 






9 


712 


580.31 


12.50 


31.50 


207.63 


26.25 


858.19 


80 . 






15 


1,072 


953.91 


19.00 


52.50 


346. IS 


39.46 


1,411.05 


83 . 






8 


591 


443.25 


5.00 


28.00 


149.88 


22.50 


648.63 


85 . 






4 


262 


209.60 


2.50 


14.00 


52.44 


9.84 


288.38 


106 . 






11 


103 


77.25 




5.25 


11.64 


3.75 


97.89 


108 . 






10 


770 


630.50 




13.50 


259.67 


29.06 








Ill . 






13 


1,199 


910.21 


25.50 


45.50 


301.38 


45.00 


1,327.59 


Total 






76 


5,946 


4,757.65 


119.50 


244.50 


1,571.71 


222.72 


6,916.08 



Average cost of planting per acre $91 

Add grading and preparing land 35 

Total ■. 126 

This will vary as the number of trees vary. This 
report shows average of 78 trees per acre. Frequently 
there are 90 trees planted per acre : 

First year's care $38.50 

Second year's care 42.50 

Third year's care 57.50 

Fourth year's care 95.00 

Fifth year's care 115.00 

348.50 
126.00 
474.50 

In the case of Navel oranges, the orchard should 
yield a scattering of fruit the third year and a consider- 
able amount the fourth and fifth years. Valencia 
oranges are later in coming into bearing. 

1 Speech of Senator J. D. Works, " Congressional Record," 
July 24, 1913. 

M 



.1(32 



Citrus Fruits 



Statement No. 1 

Cost of bringing 163 acres of lemon grove into bearing, trees planted 
in 1905 by the Riverside Trust Co. {Ltd.) 1 



Year ended Sept. 30, 1905 : 

Land and water, 163, acres, at $450 

Plowing and leveling 

Fluming 

12,608 trees, at $1 

Planting 

Cultivation and irrigation 

Fertilizing 

Water dues 



Total 
Management 



Year ended Sept. 30, 1906 : 
Cultivation and irrigation 
Fertilizing 
Water dues 
Taxes . . 
Other expenses 
Total . . 
Management . 

Year ended Sept. 30, 1907 : 
Cultivation and irrigation 

Fertilizing 

Water dues 

Taxes 

Other expenses . 

Total 

Management 



per acre 

$1,017.36 

4,310.31 

12,608.00 

957.04 

107.53 

71.40 

87.17 

19,158.81 
113.80 



1,238.72 
1,361.79 

804.65 
369.92 
953.75 

4,728.83 
788.03 



1,548.05 
734.64 

1,036.41 
794.40 
536.78 

4,650.28 

1,777.29 



$73,350.00 



19,272.61 



5,516.86 



Carry forward 



6,427.57 
$104,567.04 



1 J. D. Works, loc. cit. 



Planting the Orchard 163 

Brought forward . . . $104,567.04 

Year ended Sept. 30, 1908 : 

Cultivation and irrigation . . • $l,9b7.yy 

Pruning 205.15 

Fertilizing 2,522.25 

Water dues nio'kl 

frnYPs 773.51 

laxes ^00,42 

Other expenses ouy.<±* 

Total 6 «™qi 

Management I,b70.91 

8,427.23 

Year ended Sept. 30, 1909 : 

Cultivation and irrigation . . . 2,493.20 

Pruning lemons 125 .3d 

Fumigation (90 acres) 1,423.1 J 

Fertilizing 411.18 

Water dues J'SSw 

Taxes '2™X 

Other expenses 509.55 

Total .... 7,561.69 

* otal \ 2 52143 

Management ^' ,Jwl - w 

10,083.12 

Total $123,077.39 

Less crop returns 1908 .... 1,069.50 
Less crop returns 1909 .... 4,431.0b 

5,500.56 

Total $117,576.83 

Average, $721.33 per acre. 

These figures should be considered in connection with 
those given on pages 360 to 362. These tables present 
typical actual expense accounts while the figures given in 
Chapter XX represent the averages of very large numbers 
of ranches or packing-houses as the case may be. The 
consideration of averages alone often leads to incorrect 
conclusions, particularly with agricultural operations where 
the personal factor enters so largely into the account. 



•164 Citrus Fruits 

Statement No. 2 

Cost of 163 acres of lemon groves, by the Riverside Fruit Co. {Ltd.) 

Cost of land and water, at $450 per acre . . . $73,350.00 
First year : 

Proportion of cost of equipment, building, stock, 

tools, machinery, etc., at $82 per acre . . . 13,366.00 

Cost of planting, care, etc 19,272.61 

Second year, cost of care, etc 5,516.86 

Third year, cost of care, etc 6,427.57 

Fourth year, cost of care, etc 8,427.23 

Fifth year, cost of care, etc 10,083.12 

Total 136,443.39 

Less : 

Crop returns, fourth year .... $1,069.50 
Crop returns, fifth year .... 4,431 .06 

5,500.56 

Total $130,942.83 

Average, $803.33 per acre. 

Statement No. 3 

Cost as per statement No. 2 $130,942.83 

Interest at 6 per cent per annum : 

Five years on $86,716 $26,014.80 

Four and one-half years on $19,272.61 5,203.60 
Three and one-half years on $5,516.86 1,158.50 
Two and one-half years on $6,427.57 964.10 

One and one-half years on $7,357.73 662.20 

Six months on $5,652.06 .... 169.56 

34,172.76 

Total 165,115.59 

Average, $1,012.96 per acre. 



CHAPTER XI 

CULTIVATION, FERTILIZATION, AND COVER- 
CROPS 

The operations incident to the care and management 
of orchard soils constitute a very important part of the 
work of producing citrus fruits. Upon the intelligence 
used in the handling of the soil will depend to a large 
extent the degree of success finally achieved. 

Tilling the soil (1) improves its physical condition by 
loosening it and extending the rooting area ; (2) aids in 
saving moisture by enlarging the water-holding capacity 
and by checking surface evaporation ; (3) augments 
chemical action by making inert plant food available ; 
and (4) admits air to the soil. This last function of tillage 
is very important because plant roots must have air in 
order to grow, and air in considerable quantities is also 
essential for the life of all the beneficial bacteria upon 
which we depend for the making available of inert plant 
food in the soil and for the acquisition of nitrogen from 
the atmosphere. 

PLOWING 

The tillage of citrus orchards consists of two kinds of 
operations known as plowing and cultivating. The land, 

165 



-166 Citrus Fruits 

in most cases, should be plowed thoroughly once a year, 
preferably in March or April, which is the time the winter 
cover-crop is turned under. 

This plowing should be completed before the trees come 
into full bloom, as the unavoidable cutting of many roots 
at such a time is apt to interfere with the setting of the 
fruit. A mold-board plow is usually the best tool, and 
for plowing close up under the branches a special plow with 




_i*<i<- •* 



Fig. 48. — Cultivating newly set orange trees with eight chisel cultivator. 

one handle is very convenient. The disk plow is very 
satisfactory in some soils and especially in orchards of 
small trees. The proper depth to plow is usually about 
eight or nine inches. It is unwise to plow at the same 
depth every year, for this is apt to encourage the forma- 
tion of what is known as a plow-sole or hard layer which 
in time becomes impenetrable to water and air. Such a 
plow-sole may be largely avoided by plowing seven inches 
deep one year and nine or ten inches the next. Plow-sole 
once established may be broken up by running a subsoil 



Cultivation, Fertilization, and Cover-Crops 167 

plow fifteen inches deep, once down the center of the 
middles between the tree rows and again at right angles. 
Such treatment will cut a good many roots of course, but 
only those which extend beyond their legitimate feeding 




Fig. 49. — Cloddy condition due to land being worked while too wet. 



ground. Such subsoiling should be followed immediately 
by copious irrigation. 

When the cover-crop is tall, a heavy iron chain sus- 
pended between plow beam and single-tree will serve to 



1(58 Citrus Fruits 

hold the mass of vegetation down until caught by the soil 
and a much more satisfactory covering of the crop will 
result. The disk harrow should follow the plow, crushing 
down the loose soil and bringing it into close contact with 
the mass of green vegetation. This will result in a more 
uniform incorporation of the crop with the soil. In Cali- 
fornia there need be no fear of souring the soil by turning 
under a rank, green crop, for the large amount of , lime 
present in the soil quickly neutralizes any acid which 
may form. 

Plowing cannot be carried on as rapidly as cultivation 
and it is often very difficult to complete the spring plow- 
ing before the land gets too hard and dry to plow with- 
out much extra labor and the turning up of tremendous 
clods which are a nuisance the rest of the season. In 
such cases it is a good plan to run over the entire acreage 
first with a disk harrow, going in both directions, chopping 
up the cover-crop, and creating a light mulch on the sur- 
face which will retard evaporation and hold the land in 
good condition to plow for a longer time. By the use of 
the orchard tractor also a larger area of land may be 
plowed in a given time. 

In order to keep the ground level it is necessary to plow 
toward the trees one year and away from them the next. 

CULTIVATION 

Citrus trees are grown on irrigated lands, and as irriga- 
tion and cultivation go together, it follows that upon 
proper cultivation depends much of the success of the 
orchard. If water is applied and the land left without 



Cultivation, Fertilization, and Cover-Crops 169 

cultivation, the surface soil bakes hard, cracks open, the 
moisture escapes, and the trees suffer. It is the custom 
to cultivate after each irrigation just as soon as the 
ground is dry enough to stir without puddling. The 
irrigation furrows are obliterated by the cultivator and 




Fig. 50. — Ground under trees may be worked with ease by means of 
an orchard tractor. 



the surface four inches thoroughly stirred. In many 
cases it is advisable to follow the first cultivation with a 
second at the end of two weeks. In the case of square 
plantings the second cultivation should be carried on at 
right angles to the first. Cultivation should be deeper 
on heavy than on light soils for the reason that it requires 



'170 Citrus Fruits 

a somewhat thicker mulch to prevent the loss of moisture 
from heavy soils. In the event that the weather is very 
hot and dry immediately after cultivation it may not be 
necessary to cultivate again before the next irrigation, 
for the reason that the mulch is more effective when very 
dry. When cultivation is followed by a period of cool, 
foggy weather, the capillary connections may be re-formed 
and much loss of moisture result unless a second cultiva- 
tion be given. The object of cultivation is to create and 
maintain an effective soil mulch and the soil stirring process 
should be carried just far enough to achieve this object. 
Cultivation is an expensive operation and much money 
is wasted by the system of continuous stirring of the soil 
as practiced by some growers. 

Disk cultivators are satisfactory in adobe and silt soils 
and especially among small trees, but it is not well to 
depend upon disk implements exclusively. An occasional 
cultivation with narrow chisel teeth will bring about 
better aeration and prevent the soil from packing. 

All tillage implements used in citrus orchards should, 
be provided with carefully made shields which protect 
the low hanging fruit and prevent it from being knocked 
and scarred by striking sharp projections of the imple- 
ments as they pass close under the branches. 

Orchard soils may be very seriously injured by culti- 
vation at the wrong time, that is, when too wet or too dry. 
Immediately after irrigation there is a period of variable 
length when the soil is too wet to stir. If cultivated when 
too wet, the physical condition will be ruined. Soil is too 
wet to cultivate when it is muddy or scours off the plow 
with a slick, wet appearance. An adobe soil is injured 



Cultivation, Fertilization, and Cover-Crops 171 

more than a sandy soil by stirring when too wet. It may 
take a year or more to restore the physical condition 
ruined by injudicious cultivation. Ordinary or medium 
soils should be ready to cultivate about five or six days 




Fig. 51. 



Orchard tractor doing the work of eight mules in a hot 
desert valley. 



after irrigation, and they remain in good condition for 
about a week, after which they become too dry. If not 
stirred at the right time, the soil will bake hard and be 
very difficult to handle. If extra mules are then put on 
the cultivator, the soil will be turned up in large clods 



172 Citrus Fruits 

which will bake into brick-like masses which will be in 
the way for a year or more. 

It is often very difficult to cultivate the entire acreage 
at the proper time on account of the lack of men and 
teams. In too many cases one-fourth the ground is 
stirred while too wet, one-half when the soil is just right, 
and one-fourth after the soil has become too dry. The 
remedy for this is to either increase the equipment of men 
and mules or to have recourse to the orchard tractor, 
which makes it possible to cover a much larger area in 
the same time. This difficulty is not serious with those 
growers who irrigate from local wells. They are in a posi- 
tion to irrigate a small piece of land at a time and follow 
the irrigation with cultivation after the proper interval. 

In old bearing orchards the trees cover most of the 
ground and hardly more than a strip in the middles in 
each direction can be cultivated with teams or tractors. 
It then becomes necessary to do a considerable amount of 
hand work. The ground under the trees should be 
thoroughly worked over once a year, preferably in the 
spring just after the winter rains are over. Either a light 
spading fork or a short-handled mattock may be used. 
Workmen should be cautioned not to strike the trunks of 
the trees or the crown roots, as wounds made in this way 
are very apt to become infected with brown-rot gum- 
disease. The irrigating furrow nearest the trunk should 
pass just beneath the outer branches and the soil imme- 
diately about the trunk will not be wet during summer — 
hence the necessity of hand hoeing to furnish a mulch 
and prevent the soil about the crown from baking as hard 
as a pavement. 



Cultivation, Fertilization, and Cover-Crops 173 

MULCHING 

The great difficulty of handling heavy and intractable 
adobe soils or soils which acquire an adamantine hardness 
when dry has led some growers to substitute a mulch of 
straw or other humus forming material, for the soil 
mulch, and discontinue cultivation of the middles with 




Fig. 52. — Heavy plowing with an orchard tractor of the caterpillar type. 



teams. Permanent basins are made around each tree of 
a diameter approximating the extreme spread of the 
branches. One permanent irrigating furrow extends down 
either side of the tree row and connects with each basin. 
A permanent strip of alfalfa occupies all of the available 
space of the middle. The alfalfa is mowed five or six 
times each season and thrown into the basin under the 
trees before it is dry enough to shatter. This material 



174 Citrus Fruits 

accumulates during summer and, after acting as an effec- 
tive mulch, rots down during the winter rains and may be 
worked into the soil with hand hoes each spring before 
the new crop of mulching material is available. The 
alfalfa is sown broadcast and is irrigated by flooding be- 
tween slight ridges which bound the strip. In California 
this system is still in the experimental stage, although 
modifications of it have long been used in other countries. 

ORCHARD TRACTORS 

The availability in California of large quantities of 
cheap fuel oils has made possible a great increase in the 
use of orchard tractors. There are a number of these 
machines now on the market, some of which have proven 
economical and satisfactory. While the mule is by far 
the most flexible motor for small jobs and for work on 
broken ground such as contour plantings, the tractor is 
gradually displacing the mule on large tracts of level land. 
A grower who keeps sixteen head of mules worth $2400 
may retain four for light work and with the money from 
the sale of the others get a machine which will do the 
work of the original sixteen. The engineering of such a 
machine appeals much more strongly to the average farm 
boy than hitching, unhitching, and feeding the mules 
morning, noon, and night ! The tractor also is immune 
to the high heat of the interior valleys, which is often 
embarrassing to work-stock. With a tractor it is possible 
to till a larger proportion of the orchard area at the right 
time. 

The work in citrus orchards demands a low down, 



Cultivation, Fertilization, and Cover-Crops 175 

light, short-turning gas tractor either of the three wheel 
or caterpillar type. The machine should not exceed five 
feet in height and should be provided with steel hood or 
limb protector. Extra strong tillage implements must be 
used with tractors, as otherwise serious breakage may 
result when stones or stumps are struck. An ordinarily 
good orchard tractor should plow about twelve acres of 
orchard a day at a cost, including an ample allowance for 
interest and depreciation, of not over $12. 

FERTILIZATION 

Perhaps no subject connected with citrus fruit culture 
is hedged about with as much uncertainty as that of fer- 
tilization of the soil. California soils are usually very 
rich in available plant-food, and in many cases fertiliza- 
tion is not needed for the first few years. The average 
orchard, however, will begin to fail after five or six years 
of production unless fertilization of the soil is resorted to. 
How much and what kinds of fertilizer to apply are ques- 
tions which are extremely difficult to answer specifically, 
and it is usually necessary for each grower to experiment 
on his own land in order to gain an idea of the best course 
to follow in his particular case. No one should be dis- 
appointed if results fail to appear quickly, for with citrus 
trees on rich land it often requires a number of years 
before any measurable differences due to experimental 
fertilization can be observed. 

There is a very widespread idea among persons not well 
grounded in the principles of agriculture, that the logical 
procedure is to take samples of the soil to a chemist for 



176 



Citrus Fruits 



analysis, and to lay out a well calculated program accord- 
ing to his report. Such a course is not often practicable, 
however, for the reason that while the chemist may show 
the exact amount of plant-food in the soil, he has as yet 
no way of measuring the amount of plant-food which 
trees on a given soil may be capable of taking up. And 




Fig. 53. — Substituting baled lima bean straw for manure in lemon 
orchard near Whittier, California. 



there are still other difficulties, such as the trouble ex- 
perienced in obtaining a sample which fairly represents a 
considerable area of land, and the variation in the com- 
position and physical make-up of the soil on the same 
farm and often in the same field. Of course chemical 
analyses are valuable guides in the case of unusual soils, 
as when alkali is suspected or when some one of the neces- 
sary elements is markedly deficient. But the claims of 



Cultivation, Fertilization, and Cover-Crops 177 

some people, that the proper formula should be made up 
by adding a little of " this" to make the fruit set, and a 
little of " that" to increase the sugar content, and a little 
of "the other" to improve the color, are very largely 
without foundation of scientific evidence. 

A ton of fresh oranges and lemons removes the follow- 
ing amounts of plant-food from the soil : 



NlTBOGEN 



Phosphoric 
Acid 



Potash 



Oranges 
Lemons 



3.88 lb. 
3.04 lb. 



1.06 lb. 
1.16 1b. 



4.22 lb. 
5.08 lb. 



Citrus growers, as a rule, do not limit themselves to 
replacing the amount of plant-food removed from the 
land, but commonly apply as fertilizer many times this 
amount of plant-food. 

A study of soil analyses teaches us that when the 
average California soil begins to fail from heavy produc- 
tion nitrogen is most likely to be the first crop limiter 
and after nitrogen phosphoric acid, and after that potash. 
Most important of all, however, is the physical condition 
of the soil, for all of these elements may be present in 
excessive amounts ; and yet if the physical condition of 
the soil is not favorable to a vigorous and healthy root 
action, the plant-food present cannot be used. By proper 
physical condition is meant that state in which the soil 
will absorb water quickly and hold it long as well as admit 
air to considerable depths. 



178 



Citrus Fruits 



A Type of Fertilization Practice in Southern California 
for Old Bearing Trees which are Too Close to Permit 
Cover-crop 



Variety 


Kind of 
Fertilizer 


Lb. per 
Tree 


How Applied 


Date of 
Application 


Navels 


Bone meal 


7 


Drilled in 


Oct., 1912 


Lemons 


Bone meal 


6 


Drilled in 


2.5% N 


Tangerines 


Bone meal 


8 


Drilled in 


22% P 2 6 


Navels 


Sodium nitrate 


2 


Hand spread 


Mch., 1913 


Lemons 


Sodium nitrate 


2 


Hand spread 


Buds just 


Tangerines 


Sodium nitrate 


2 


Hand spread 


starting 


Navels 


Tankage 


12 


Drilled in 


Apr., 1913 


Lemons 


Tankage 


12 


Drilled in 


8.35% N 


Tangerines 


Tankage 


15 


Drilled in 


7.65% P 2 5 


Navels 


Stable manure 


5 cu. ft. 


Disked in 


Aug., 1913 


Lemons 


Stable manure 


5 cu. ft. 


Disked in 




Tangerines 


Stable manure 

Same as for 
1912 


5 cu. ft. 


Disked in 


Oct., 1913 



HUMUS 

Humus is a dark colored highly complex organic com- 
pound which is formed by the decay of vegetable matter 
in the soil. Humus is present in relatively small amounts 
in California soils, because on account of their greater 
ventilation and higher temperatures the humus is oxidized 
or burned out of the soil more rapidly and does not accu- 
mulate to the extent it does in the soils of humid and 
cold climates. The chief reason why humus is so im- 
portant is found in the fact that it is relatively insoluble 



Cultivation, Fertilization, and Cover-Crops 179 

under good field conditions and does not leach away, but 
remains to form the food of nitrogen-forming bacteria 
which convert it by degrees into nitric acid, which, while 
one of their waste products, yet is the essential form of 
nitrogen for the food of citrus trees. Humus also has 
tremendous water-holding capacity and its presence en- 
ables the soil to take up water like a sponge. Humus has 
the tendency to make close compact soils more open and 
porous, and at the same time sandy soils are made more 
retentive of water. 

It happens also that the average humus of arid soils 
contains about three times as much nitrogen as that of 
humid soils, and therefore it is especially important to 
maintain the humous content of arid soils. On account of 
the fact that the humus in California soils is so intimately 
associated with nitrogen formation, we are warranted in 
saying that where the humus and moisture conditions of 
a soil are kept at the optimum, the question of nitrogen 
fertilization becomes of less importance, especially where 
heavy crops of leguminous green manure are practicable. 

The humous content of soils may be kept high by the 
application of vegetable matter in various forms. Stable 
manure, bean straw, alfalfa hay, trash and sweepings of 
many sorts, leaves, kelp, cover-crops, weeds, prunings, 
citrus fruit culls — all these are used to supply decaying 
organic matter to the soil. When the humus is too low, 
the soil, if sandy, loses water too rapidly; if heavy, it 
becomes cloddy, dead, inert, and bakes quickly after irri- 
gation. Such a soil is hard to cultivate, forms a plow- 
sole quickly, and it becomes more and more difficult to 
get the water to sink in rapidly. The trees make small 



180 



Citrus Fruits 



growth, and as the tops become thin, numerous water 
sprouts push out from the trunk. The fruit is small 
and appears to be more susceptible to splitting and sun- 
burn. Too much humus (a condition very rare in arid 
countries) causes too great a vegetative growth at the 
expense of fruit wood, while the fruit tends to grow large, 




Fig. 54. — Cull oranges used as a humus-forming fertilizer. 



coarse, thick-skinned, and poor flavored. The optimum 
amount of humus for citrus trees in California has not 
been determined with any degree of certainty. No doubt 
it varies with the distance from the coast, being higher in 
the hot, interior valleys. It is suggested that manure, or 
its equivalent in other vegetable matter, to the depth of 
two inches over the entire surface of the land once a year 



Cultivation, Fertilization, and Cover-Crops 181 

would not be too heavy an application on the type of 
soils common around Redlands and Riverside, although 
somewhat smaller amounts should answer for soils nearer 
the coast. 

As a matter of practice it is very difficult to secure 
anything like adequate supplies of humus-forming ma- 
terials. Although enormous amounts of manure are 
bought at high prices in the cities and shipped to the 
citrus ranches by rail, only a small percentage of the 
orchards are manured every year. In order to make up 
the deficiency, the growing of green manure crops has 
been largely resorted to. 

GREEN MANURE CROPS OR COVER-CROPS 

Cover-crops in the citrus orchard have many ad- 
vantages and few disadvantages. 

Advantages — 

1 . They increase the fertility of soil by the addition of 
humus which acts as a liberator of mineral nutrients ; 

2. Increase the water-holding capacity ; 

3. Make the land easier to work by improving physi- 
cal condition ; 

4. Encourage an increase in number of soil bacteria; 

5. Add nitrogen directly to the soil from the air when 
such crops are leguminous ; 

6. Puncture the plow-sole with roots which decay and 
leave openings for the admission of air and water; 

7. Bring plant-food up from below and leave it near 
the surface; 



182 Citrus Fruits 

8. Prevent excessive erosion on steep hillsides; 

9. May decrease the amount of brown-rot. 

Disadvantages — 

1. They may necessitate irrigation at times not good 
for citrus trees. 

2. Heavy root-pruning of trees incident to turning 
under cover-crop is not advisable while trees are blooming 
and setting fruit. 

3. They may increase cottony-mold in case the cover- 
crop used is a host for this fungus. 

A large number of different crops have been experi- 
mented with, but the ideal plant for this purpose has not 
yet been found. Some of the plants in use are, in the 
order of their importance, common vetch, Canada field 
peas, bur clover, fenugreek, hairy vetch, sour clover, 
alfalfa, buckwheat, and cowpeas ; the last named crop 
being grown only in summer. 

Common vetch, Vicia sativa, is by far the most com- 
monly grown crop. It has large seeds which germinate 
well, and grows throughout the winter. It has the dis- 
advantage of maturing rather late in spring and is in 
some cases a host for the cottony-mold fungus. In 
recent years it has been seriously injured and in many 
cases destroyed by a species of aphid. For these reasons 
the use of common vetch is on the decline. 

Recent experiments have shown that purple vetch, 
Vicia atrojnirpurea, is better than common vetch and it 
is to be hoped that an adequate supply of seed will soon 
be available. 

After an irrigation in the first half of September, the 



Cultivation, Fertilization, and Cover-Crops 183 

soil is well cultivated and fifty to one hundred pounds 
per acre of vetch seed is either deeply drilled in both 
directions or sown broadcast, after which the irrigation 
furrows which are to remain all winter are immediately 
laid off as close together as possible. 

If planted in October or later, the plants do not get 
sufficiently well started before cold weather to make 
much growth during the winter. In northern California, 
under irrigation, vetch should be sown about the first of 
October. It will then make a sufficient growth to be 
turned under in February or March. 

In the citrus districts of northern California vetch is 
used to a small extent only, as the volunteer crop of bur 
clover is often very satisfactory. In many places a 
common weed, maha, comes volunteer and growing to a 
height of three or four feet produces a large tonnage of 
green stuff. This plant is not a legume, but makes up in 
quantity what it lacks in quality. Other weeds which 
sometimes make good cover-crops are erodium, known as 
"filaree" and a chenopodium. 

In southern California a winter cover-crop of some kind 
is the rule on all except the very stiff adobe soils near 
the coast. Such soils are injured in texture by lying 
without cultivation all winter, and consequently manure 
is used to the exclusion of a cover-crop, and the cultiva- 
tors are kept moving all winter. 

The question is often asked whether it is not advisable 
to inoculate seed to be sown on land that has not pre- 
viously grown that crop. In California, it has been found 
that the bacteria necessary to nodule formation on the 
more common leguminous crops are present in most soils. 



184 Citrus Fruits 

The first seeding may not, however, be as abundantly 
inoculated as desired, and in some sections the bacteria 
essential to certain crops seem to be entirely lacking. In 
such case the land should be inoculated by drilling in with 
the seed a small quantity of fresh soil taken from some 
field which has grown the particular crop satisfactorily. 

A few growers who have sufficient water grow a sum- 
mer crop of cowpeas in addition to the winter crop. 
This of course is advisable where practicable, but on ac- 
count of the higher price of summer water and the need 
of most soils for frequent stirring, the practice is con- 
siderably limited. In the northern part of the Sacra- 
mento Valley, where water is cheap, the practice of plant- 
ing the orchards permanently to alfalfa is on the increase. 
As yet this can only be regarded as an experiment and 
should not be adopted on a large scale at the present 
time. 

SUMMARY 

In summing up this discussion of soil management it 
may be said that optimum production depends upon a 
number of factors working together. As a chain is only as 
strong as its weakest link, so the size of the crop cannot 
rise above the one factor which is farthest from the 
optimum. The effort of every grower should be to dis- 
cover the "crop limiter" in his particular grove. First 
he should provide plenty of water to dissolve the plant 
food and carry it into the plant. Then he should increase 
the humous content to the point where his soil is actually 
"alive" with bacteria working to fix for him the free 
nitrogen of the air and make available the tremendous 



Cultivation, Fertilization, and Cover-Crops 185 

stores of inert plant-food in the soil minerals. This 
should be done by the application of manure or straw 
and the growing of leguminous cover-crops. The soil 
should be deeply plowed and cultivated in order to en- 
courage the roots to go down after the plant-food which 
in arid soils is available at unusual depths. The arid 
soil farmer has a great advantage in this regard, and this 
advantage should not be thrown away by shallow irriga- 
tion and cultivation. 

After all this is done it is time to consider the kinds 
and amounts of commercial fertilizers to apply. This 
will be found a puzzling question and one which must be 
largely determined by each individual grower for him- 
self. He should first experiment by trying out each 
plant-food element alone. A few rows should receive 
nitrate of soda, a few phosphoric acid, and a few sulphate 
of potash, with check rows receiving nothing alternating 
with the fertilized rows. It will require a number of 
years' patient effort perhaps before results will be evident. 
Having found the element or elements to which his trees 
respond, his next step is to determine the optimum 
amount of such fertilizers which it is profitable to use at 
the price he has to pay for them. 

Meanwhile the grower should apply to the remainder 
of his acreage, not included in the experiment, a fair 
amount of fertilizer as determined by the amount of 
nutrients removed in the crop, modified to some extent 
perhaps by the former results and experience of other 
growers in the immediate neighborhood. 

While fertilization is a very important part of the 
process of producing citrus fruits, too great or too quick 



186 Citrus Fruits 

results should not be expected. A few extra pounds of 
fertilizer should not be expected to overcome the injury 
done by neglect or carelessness in irrigation, cultivation, 
or pruning. There is an old Roman proverb which applies 
especially well to citrus fruit raising. It is somewhat as 
follows : 

"The footprints of the owner make the best fertilizer." 



CHAPTER XII 



IRRIGATION 



In all parts of the arid Southwest citrus fruits require 
irrigation. In many localities in California, especially 
where the rainfall is heavy, deciduous fruits, such as 




Fig. 55. — Canal lined with cement. Transformation of desert hills 
into orange groves. 

187 



188 Citrus Fruits 

prunes, peaches, walnuts, grapes, and almonds, are grown 
very successfully without irrigation. The very deep rich 
soils not only encourage deep rooting, but they constitute 
a reservoir for the winter rainfall which is, or should be, 
carefully conserved for the use of the trees by frequent 
surface cultivation during summer. Citrus fruits, how- 
ever, being evergreen, transpire large amounts of water 
at all seasons of the year ; and while in the more favored 
locations the trees may remain alive, they should not be 
expected to bear commercial crops without irrigation 
water in addition to the rainfall. 

AMOUNT OF WATER NEEDED 

The amount of water needed will depend upon the 
amount of rainfall, the character of the soil, the climatic 
conditions, and the age and kind of trees. Heavy clay or 
adobe soils are usually difficult to saturate, but once well 
soaked they retain the water well, and a less amount is 
needed on such soils than on open gravelly soils through 
which the water passes more readily. Near the coast, 
where the air is moist, trees require somewhat less water 
than in interior valleys where it is more windy and the air 
is hot and very dry in summer. The draught on the tree 
for water varies with four factors : the temperature, rela- 
tive humidity, velocity of wind, and the amount and inten- 
sity of the sunlight. The observers of the United States 
Weather Bureau record all of these factors, but apparently 
no systematic attempt has been made to correlate them. 
The porous-cup atmometer automatically correlates all 
of these factors, the record indicating in cubic centimeters 



Irrigation 



189 



of water evaporated per day, the total demand of the air 
on the plant for water. The writer kept duplicate atmom- 
eter records for one year at Whittier and Riverside, 
California, for the purpose of measuring this difference 
in the climate of the two places. Whittier is in Los 
Angeles County, about fifteen miles from the coast, 
and situated on the foothills facing the sea. Riverside is 
about thirty-five miles due east of Whittier and on the 
opposite side of the hills. 

Atmometer Records June 1, 1911, to May 31, 1912 



1911, June 
July 



1912, 



August 
September 
October 
November 
December 
January 
February 
March 
April 
May 
Total . 



Average daily 



Whittier 


Riverside 


686.0 cc. 


1,302.1 cc, 


779.1 


1,301.0 


934.8 


1,244.3 


852.7 


1,421.7 


989.7 


1,249.7 


1,544.0 


1,541.4 


1,279.3 


1,371.3 


1,319.5 


1,211.1 


1,025.0 


1,019.8 


654.6 ! 


620.4 


464.8 


1,017.9 


707.2 


1,643.4 


11,236.7 


14,944.1 


30.7 


40.9 



1 Estimated from incomplete records. 



These figures show that the draught of the air for water 
is about 33 per cent greater at Riverside than at Whit- 
tier, and this fact considered in connection with the 



190 



Citrus Fruits 




Fig. 56. — Preparing the ground for furrow irrigation. 
(From U. S. D. A., Farmers' Bui. No. 404.) 



more porous character of the Riverside soils explains 
why a larger quantity of irrigation water is needed. 

Of course it goes without saying that old bearing trees 
require much more water than young trees, and it is essen- 



Irrigation 191 

tial for permanent success that the right to sufficient 
water for old trees be secured in the beginning and jealously 
guarded until it is all needed. As a basis for estimating 
the capacity of wells and streams, the available flow during 
the driest years on record should be taken. The rainfall 
is variable and it is not unusual for several dry years to 
occur in succession. At such times the underground 
stores of water are greatly depleted and the trees are apt 
to suffer. 

Inasmuch as the average yield in pounds of mature 
lemon trees is considerably greater than that of orange 
trees, it follows that they require more water, and this is 
borne out by the experience of the growers. 

From what has been said it is clear that no definite 
rule can be laid down as to the exact amount of water 
needed under different conditions. For the sake of com- 
parison, however, it may be stated in a general way that 
water to a depth of from thirty-five to forty-five inches, 
including both irrigation and rainfall, should be allowed 
bearing citrus trees. Full bearing orchards on retentive 
soils near the coast should be provided with about one 
and one-fourth ordinary miner's inches to each ten acres, 
while the same trees in the hot interior valleys and es- 
pecially on gravelly soils should have not less than three 
ordinary miner's inches to ten acres. 

The miner's inch in California has two values. The 
ordinary one adopted by custom is a stream flowing 
freely through an opening one inch square under a pres- 
sure head of four inches on the center of the opening. 
This flow is equivalent to one-fiftieth of a cubic foot per 
second or nine gallons per minute. The miner's inch as 



192 Citrus Fruits 

defined by the statute of 1901 and known as the "Statute 
Inch" is equivalent to a stream flowing freely through 
an opening one inch square under a pressure head of six 
inches on the center of the opening. This flow is equiva- 
lent to one-fortieth of a cubic foot per second or eleven 
and one-fourth gallons per minute. All contracts for 
water should specify the miner's inch to be used. 



SOURCES AND COST OF WATER 

Water for citrus orchards is secured by diversion from 
flowing streams, by pumping from reservoirs in under- 
ground gravel beds, and from artesian wells. The best 
water rights are old and well established claims to stated 
quantities of water from streams which are fed the year 
round by melting snows of high mountains. The right 
to a water supply pumped from wells is good provided 
the land to be irrigated overlies the underground reser- 
voir, the owner of such land having an equal right with 
other overlying land owners. In cases where the surface 
of the ground immediately over the reservoir is not suited 
to cultivation the water may be transported for use upon 
any land within the same natural drainage area. The 
right to transport water from one natural drainage area 
into another for irrigation purposes is questionable. 

Where a great many wells are put down in the same 
neighborhood they are apt to interfere with each other, 
and the general level of the underground water may be 
drawn down to such an extent that the pumps may have 
to be lowered and engines of greater power installed to 
lift the water to the surface. Artesian wells often cease 



Irrigation 193 

to flow under such conditions. In cases where a series of 
dry years brings about a marked diminution in the supply 
of the underground water, the lands immediately over- 
lying the water-bearing gravels have first right to the 
water; and in case these lands are not cultivated, then 
the distant lands enjoy prior rights in the order in which 
the water for them was appropriated. 

The cost of water is extremely variable, running from 
almost nothing to as high as fifty or sixty dollars an acre 
a year. With the development of cheap electric energy 
and the internal combustion engine, water may now be 
economically lifted to great heights. One large company 
near Corona, by the use of what is known as a " boosting 
plant" run by an internal combustion engine, lifts water 
to a height of 750 feet for the irrigation of lemon orchards. 

The average cost of water used in citrus orchards in 
California is about twenty dollars an acre a year. 

METHODS OF DISTRIBUTION 

In the early days water was distributed to the high 
places throughout the orchards through open ditches and 
viaducts. These were very unsatisfactory because they 
filled up with grass, weeds, and silt and ]$f& to be cleaned 
out quite often. Not only was this expensive, but a 
great deal of water was lost, by seepage. These ditches 
were replaced by wooden flumes, which answered well 
until they rotted out. They have been gradually replaced 
by concrete pipe-lines, which are now almost universally 
used in the citrus orchards of California. If well made 
of one part of cement to four parts of clean, sharp sand 



194 



Citrus Fruits 



this pipe is permanent and has proved highly satisfactory 
wherever the pressure is not over ten feet. It is laid 
about fifteen inches below the surface or deep enough to 
be out of the way of the subsoil plow. The joints are 
carefully cemented to prevent leakage and the entrance 




Fig. 57. — Irrigating stands in operation. 



of roots. Where the pressure is greater than ten feet, 
steel pipe must be used. Concrete pipe twelve inches in 
diameter costs about thirty-five cents a foot, laid. 

The pipe-lines are laid across the rows and at the end 
of each row a standpipe is placed over the line in such a 
way that the water will rise to a certain height and over- 
flow back into the line. Each standpipe is furnished with 



Irrigation 195 

delivery spouts controlled by close-fitting metal gates. 
The overflow provides for an even pressure on the delivery 
spouts at all times. 

Where the check system is used the water is delivered 
at the highest corner in a large head and conveyed to 
different parts of the orchard through temporary earth 
ditches. 

TIME OF APPLICATION 

Citrus trees should never be allowed to suffer for water. 
Olive trees, aside from dropping the fruit, are not per- 
manently injured, but citrus trees receive a setback which 
it often takes years to overcome. The soil should be 
watched and water applied before the trees show any 
signs of distress such as curling of the leaves or dropping 
of the fruit. It is very important that the grower keep 
in close personal touch with the condition of the soil to 
the depth of four or five feet. The only way to find out 
the condition of the soil is by digging holes at various 
places or by using the King soil sampler. 

Where growers take the water from a company serving 
a large area, they usually irrigate in rotation about once a 
month during the summer and less often during the rainy 
season. This system is objected to on the ground that 
there is not an incentive to use water economically. 
While the trees are small and the supply of water is greater 
than necessary there is a tendency to try to make amends 
for poor cultivation by over irrigation. 

Experienced growers are able to determine when a soil 
needs water by simply feeling it in the hands. Beginners, 
however, should make physical tests of the water content 



-196 Citrus Fruits 

occasionally. Such a test is very simple and may be 
performed by any one. Samples may be taken to a 
depth of four feet, keeping the soil from each foot separate. 
These samples are weighed immediately, and again after 
having been exposed to the hot sun for the greater part 
of a day. The difference in weight will represent the 
moisture content. It is considered that six per cent 
by weight of free moisture is sufficient, in sandy loam 
soils, to keep the trees in good condition. 

" Dr. Loughridge in his experiments at Riverside in 
June, 1905, found an average of 3.5 per cent in the 
upper two feet and an average of 6.16 per cent below 
this level in an orchard which had not been irrigated since 
October of the preceding year. It had received, however, 
a winter rainfull of about sixteen inches. On examina- 
tion it was found that the bulk of the roots lay between 
the first and fourth foot. These trees in June seemed 
to be merely holding their own. When irrigated, July 7, 
they began to make new growth. A few days after the 
water was applied, the percentage of free water in the 
upper four feet of soil rose to 9.64 per cent. The results 
of these tests seemed to indicate that the percentage by 
weight of free moisture should range between 5 and 
10 per cent in average orchard loams." 1 

The temperature of the water oftentimes has an im- 
portant relation to the health and productivity of the 
trees. Hilgard 2 has the following to say in regard to 
this : "To those who are located in or near the foothills 
and are apt to receive their irrigation water at a tem- 

1 Fortier, U. S. Dept. Agr., Farmers' Bui. No. 404, p. 24. 

2 Rpt. Calif. Exp. Sta., 1897-98, p. 54. 



Irrigation 



197 




Fig. 58. — Zigzag furrows wet the ground between the trees. 



198 Citrus Fruits 

perature not far above that at which it left the high 
Sierras, this is a very serious consideration. Many a 
time there have come to the Station complaints of an 
unaccountable dropping of fruit, or injury to field crops, 
which, when investigated, were directly traceable to the 
use of cold irrigation water, at a time when the trees and 
crops were in full growth. As the same ditch may at 
different times supply him warm or cold water, accord- 
ing to the use made of it before it reaches the lower level, 
the irrigator should use, if not a thermometer, at least 
his hand and a good slice of common sense, to determine 
whether or not he is running a risk of injury by applying 
it directlv to his land." 



METHODS OF APPLICATION 

In orchard irrigation it is necessary that the water be 
evenly divided between all the units of space both hori- 
zontal and vertical. It is desirable that the water be 
retained in the soil until taken up by the roots of the 
trees. Part of the water may escape through leaching 
into the sub-drainage, and part will evaporate from the 
surface. It should be the aim of the irrigator to reduce 
the loss through these avenues as much as possible. Sub- 
irrigation through some kind of system of pipes would 
seem to be ideal, but has been found to be impracticable, 
on account of the plugging of the openings in the pipe 
by tree roots in their natural growth toward the moisture 
in the undrained pipes. 

Overhead irrigation is being experimented with on a 
small scale by various growers, and in some cases gives 



Irrigation 



199 



promise of success. Mr. David Overholtzer of Covina 
is irrigating nine acres of twenty-two-year-old Valencia 
oranges by this method with apparent success. He lifts 
his water 147 feet or more from a well in the orchard with 
a Pomona deep well pump and a 40 H. P. gas engine. A 
centrifugal pump keeps the pressure on the line at about 
forty pounds. The supply pipes run down the center 




p IG 59 — Overhead irrigation system in old orange orchard near 
Covina, California. 

of the orchard and from them radiate the delivery pipes, 
one over every other middle at an elevation of 16 feet. 
The patent brass nozzles, yVo mcn diameter, are placed 
four feet apart, and the streams of water are thrown 
laterally about twenty feet. The entire orchard is irri- 
gated at once and the delivery pipes are all rotated from 
one windlass in the pump-house. The equivalent of one 
inch of rain is applied in about twelve hours. 



200 Citrus Fruits 

The two chief methods of application are by basins 
and furrows. Furrows are best for heavy soils, but basins 
are often necessary on sandy or gravelly soils across which 
it is impracticable to transfer the water except in very 
large heads. In loose sandy soils, water percolates with 
such rapidity near the head ditch that a large part is 
lost by passing far below the roots and possibly into sand 
and gravel strata, through which it flows away. In one 
orchard measured by Loughridge the water had per- 
colated to a depth of twenty-six feet at a distance of 
thirty feet from the head ditch. As it is doubtful if 
water at a depth of more than five feet below the root 
systems will be of any benefit to the trees, it is evident 
that a large part of this water was wasted. For these 
reasons it is advisable to use the basin system on all loose 
sandy soils. By the use of a ridger, the loose earth is 
thrown up into ridges midway between the rows in two 
directions at right angles to each other. This divides up 
the ground into a number of squares with a tree in the 
center of each. A ditch is then run from the supply line 
at the head down every alternate row by splitting the 
ridge in this row. The water is then admitted in a head 
of 40 or 50 miner's inches and run through to the lower 
two basins. After these are full, the water is admitted 
to the two above, and so on till the double row is completed. 

By far the larger part of citrus irrigation in California 
is done by the furrow method. The orchard is divided 
into sections and head lines of concrete pipe with stands 
run across the orchard from 300 to 500 feet apart. The 
distance between these is known asa" run." The length 
of these runs is governed by the size of the orchard and 



Irrigation 201 

the kind of soil. Where the soil is open and water sinks 
readily through it, 300 or 400 foot runs should be used, 
otherwise much water is lost by deep percolation on the 
upper part of the tract. On very sandy or gravelly soil 
having a slight slope, the proper length of furrows is 200 
feet, while on heavier soils with considerable grade, the 
length may be increased to 500 or even to 700 feet. The 
grade of the furrows varies widely from one per cent or 
less to ten per cent or more. The steeper the grade, the 
more likelihood of washing and consequently the smaller 
the stream of water used. On ordinary soils, a three or 
four per cent grade is preferred. Where the grade is 
more than ten per cent the furrows should be run on 
the contour. 

The number of furrows used between each tree row 
depends on the age of the trees, the distance between 
rows, the depth of the furrows, and the character of the 
soil. During recent years the general trend of orchard 
practice is toward deep rather than shallow furrows, a 
depth of eight inches being frequently used. The furrow- 
ing implement ordinarily used consists of a sulky frame 
to which are attached two or three wide shovel plows. 
Sometimes a subsoil plow is run in the bottom of the middle 
furrow and again at right angles in the center of the 
middles in order to insure deep percolation of the water. 

As the trees grow and occupy most of the space, it be- 
comes difficult to run the furrows close to the trees, and 
consequently there is a large space left in the row between 
the trees which is not wet. This trouble is met by cross- 
furrowing. While this occasions a large amount of hoe 
work in reopening the furrows where they cross, it is 



202 



Citrus Fruits 



absolutely necessary when large wide-spreading trees are 
irrigated by the furrow method. Cross-furrowing is also 
used with newly-set trees when the cost of water is such 

as to require the most eco- 
nomical use. 

After the irrigator has 
walked along the row of 
stands and opened enough 
jets to consume the head of 
water, one to each furrow, 
he proceeds to the lower end 
and awaits the arrival of the 
water. As soon as two or 
three runs are through, he 
walks across the lower end 
and takes note of the progress 
of the water in each furrow by 
number. Returning to the 
upper end, he cuts down the 
flow in those furrows which 
are "through" and increases 
the flow in the others. This 
process is repeated several 
times until just enough water 
is admitted to each furrow to 
run through but not waste at 
the lower end. All the while 
he must devote some time to locating and plugging gopher 
and mole holes, which are apt to intercept some streams, 
and to keeping a watch for " dams," which are accumula- 
tions of floating leaves which force the water to rise and 




Fig. 60. — The King soil sam- 
pler is very useful for deter- 
mining the downward progress 
of irrigation water. 



Irrigation 203 

break over from one furrow into another, thus causing 
serious trouble. After once well regulated, the water 
should not require much attention, and is allowed to run 
till the ground is soaked to a depth of four feet as ascer- 
tained by digging or pushing down the shovel handle. 
After being turned off, the water in the soil will usually 
percolate a foot or two farther, thus wetting the required 
five feet. In case the water will not soak down on 
account of the presence of a hard layer such as plow-sole 
or hardpan, this condition should be remedied at once. 
This may be done either by blasting the soil in the case of 
hardpan or by using a sub-soil plow as described above in 
the case of ordinary plow-sole. 



CHAPTER XIII 
PRUNING AND TOP-WORKING 

There is probably no horticultural operation about 
which more dogmatic advice has been given than pruning. 
Among practical citrus growers there is ,much diversity 
of opinion, and this is due in most cases to the attempt 
to master all the details without previously obtaining a 
true conception of the principles involved. 

We hear little of the " Let Nature have her way " senti- 
ment in these days of scientific horticulture. While our 
old sweet seedlings may have developed into fairly satis- 
factory trees with but little attention, the highly artificial 
Eurekas and Navels which we grow to-day are different. 
They should no more be expected to take care of them- 
selves than should a highly bred Jersey cow turned out on 
the range be expected to give her normal flow of milk. 

It is difficult to give definite detailed directions for the 
pruning of citrus trees because trees are like children, every 
one different and presenting a set of individual problems. 

In pruning citrus trees, the chief object sought may be 
stated as follows : to develop such shape and size of tree 
and strength of limb as will permit the bearing of optimum 
crops of maximum quality without damage to the frame- 
work of the tree ; which at the same time must be con- 

204 



Pruning and Top-Working 



205 



sistent with convenient and economical cultivation, 
fumigation, and harvesting. 

The first requirement in achieving the above object is 
to head the tree correctly, and in the case of balled stock 
this is done in the nursery row. 

The usual height at which citrus trees are headed is 
about thirty-three inches, although there is some variation 




Fig. 61. — A well pruned Eureka lemon orchard photographed 
August 10th. 



from this, and two or three inches higher or lower will not 
make any material difference. It is not wise to pinch out 
the bud and head the tree as soon as the shoot reaches 
the required height. It should be allowed to grow at least 
six inches taller and then cut back to the desired height. 
This will result in harder and stronger wood at the top, 
where the main branches which constitute the framework 
of the tree are to grow. This cutting back will force into 



206 Citrus Fruits 

growth a number of buds all along the trunk. Five or six 
of these should be selected for the main branches and they 
should not only be distributed on all sides but also over the 
upper thirteen inches. When two limbs join the trunk 
at the same height, they are apt to split the trunk under the 
load of fruit in later years. Whenever two branches grow 
out from one bud, one of them should always be removed. 
Every shoot which puts out from the lower twenty inches 
should be removed. It is customary to allow the big 




Fig. 62. — Prototype of California pruning saw. From Volckamer's 
" Hesperides," 1708. 



broad leaves which grow on the main trunk to remain 
until the trees are dug for sale. The main branches may 
grow out a foot or so in length, but are usually cut back 
to six-inch stubs when the trees are dug. 

When trees are dug with bare roots, the entire top is 
cut off, leaving the trunk as a straight cane. The work 
of heading the tree must then be done in the orchard. In 
some places, it has become a common practice to make 
vertical slits in the trunks of young orchard trees with a 
sharp knife. In some cases, a V-shaped blade is used 
which lifts out a small strip of bark, the idea being to re- 



Pruning and Top-Working 



207 



lease an imaginary pressure on the bark and allow the 
tree to grow faster. There is no scientific basis for such 
a practice, and while there is usually no particular harm 
done, it is unlikely that any real advantage results. On 
the other hand, trees freshly scored in this way are very 
much more susceptible to injury by frost. In the freeze 
of January, 1913, thousands of young trees were lost for 
no other reason than that they had recently been scored 
on the southwest side ; and as a result of the cold followed 




Fig. 63. — California pruning saw. Used throughout the Southwest. 

by sunshine the entire cylinder of bark came away from 
the trunk. 

From the time the young trees are planted in orchard 
form the methods of pruning oranges and lemons diverge, 
and it is best to discuss them separately. 



PRUNING ORANGES 



It has long been the custom to prune orange trees very 
little or none at all beyond the removing of water-sprouts 
and dead brush. The tree resulting from this system is 
a dense, bushy ball of foliage, growing close down to the 



208 Citrus Fruits 

ground, with the fruit distributed over the surface on the 
ends of the outer limbs and twigs, and the inside an imper- 
vious thicket of dead brush or a closely shaded open space 
if the brush has been removed. While such trees are very 
beautiful to the eye and produce fairly satisfactory re- 
sults, they fall far short of the ideal in orange pruning. 

Navel oranges of true standard type usually need little 
pruning during the first two years beyond removing water- 
sprouts. If the Navels are from poorly selected buds, a 
good many will throw up strong, rude branches which are 
often more or less thorny, and which tend to monopolize 
the tree and sap the strength of the more modest growth. 
All such shoots should be cut off early' in their career 
exactly where they began. The best branches of a first- 
class Navel tree naturally become more or less pendant 
and gradually upon such horizontal branches upward grow- 
ing shoots arise. These shoots are dimorphic in character, 
and every pruner should learn to distinguish between them. 
One form, commonly known as sucker growth, is large and 
rapid growing, reminding one of a young shoot of aspara- 
gus. The leaves are large and often resemble pomelo 
leaves. Long thorns are common, although a sucker may 
occasionally lack thorns entirely. Suckers often grow 
two or three feet in length before branching or making 
one of the characteristic nodes which mark a resting 
period. 

The other type of growth, commonly known as fruiting 
brush, is more modest. It is thick set, fine stemmed, and 
with smaller but well formed dark green leaves. This 
type of growth will branch often and form frequent nodes 
and many flower buds. The character of a shoot is not 



Pruning and Top-Working 209 

necessarily determined by its place of origin, for fruiting 
shoots often arise from the trunk or main branches and 
have access to large food supply and yet do not develop 
into suckers. They may be exceedingly vigorous and erect 
with very large leaves, and yet terminate at six inches 
in a flower bud and mature a large, more or less coarse 
skinned orange. Suckers usually arise from branches of 
some size. When they appear low down on the trunk 
they are usually called water-sprouts, although there is 
no clear distinction between the two. 

A sucker left alone will, after a few years of riotous living, 
quiet down and produce fine brush and fruit. The first 
fruit produced will be more or less coarse and inferior, but 
the quality will gradually improve from year to year. 
Many experienced growers believe that suckers will never 
produce fruit fully equal in quality to that borne by other 
parts of the tree. Some growers also claim that the pres- 
ence of a large sucker in a Navel tree will gradually bring 
about a deterioration in the quality of fruit borne on older 
parts of the tree as regards shape, color, and texture, and a 
diminution of the quantity as well. This question has 
been a common bone of contention at Farmers' Institutes 
and Fruit Growers' meetings in California for years, and 
there is as yet no accurate scientific data upon which to 
base a conclusion. 

Of certain things we are sure, however. Suckers do pro- 
duce poor fruit for several years. When suckers arise 
from a horizontal limb, they are apt to acquire great 
leverage when in fruit and often twist and split the parent 
limb. When suckers arise from upright branches they 
are usually poorly attached and are apt to split off with 



210 



Citrus Fruits 



the weight of fruit. Suckers destroy the symmetry of the 
tree and reflect discredit upon the orchardist. When a 
sucker is cut back, its nature will not be changed at once, 
for it will branch and give rise to several suckers where 
one was before. For these reasons it is clear that as far 
as the Navel orange is concerned, the best practice is to 
allow the tree to increase in size slowly and develop its 
top out of the fruiting type of growth. 




Fig. 64. — A good type of pruning saw above. Poor type below 



The two types of wood above discussed are not always 
clearly differentiated, and intermediate forms are often 
met with. Such forms are often puzzling to the amateur 
primer, whose best policy is to allow them to remain tem- 
porarily and watch future tendencies. In every case 
where the growth is clearly a sucker, and experienced 
pruners find little difficulty in distinguishing them, they 
should be vigorously suppressed. 

It is very important to keep a careful watch for bud- 



Pruning and Top-Working 211 

sports, especially in old Navel trees which have been 
propagated from carelessly selected buds. The same sport 
will sometimes appear many times on different trees in the 
same orchard, as explained in Chapter VII. Some growers 
confuse sporting branches with the dimorphic branches 
discussed above, while in reality the phenomena are quite 
distinct. Sporting involves a change in the germ-plasm 
of the cells, while the dimorphic differences mentioned 
do not. Sports may be removed while the branches are 




Fig. 65. — One of the best types of pruning shears. 



still small and the orchard thus kept true to type by prun- 
ing. Occasionally a tree may be encountered which ap- 
parently has ever-sporting tendencies. This is due to 
the fact that the mutation occurred in the trunk early in 
the history of the tree, or even on the tree from which 
the original bud was taken, and the mutative cells have 
multiplied and become distributed through various parts 
of the tree. It requires very drastic pruning to cure such 
a tree of its bad habits, and it is often advisable to pull it 
out and plant a new tree in its place. 

It is well for the pruner to bear in mind, however, that 



212 



Citrus Fruits 



while the great majority of sports are objectionable, some 
of our improved varieties have originated as sports, and it 
is therefore wise to critically examine the fruit of every 
sport discovered before destroying it. 

Valencia oranges grow in quite a different way. They 

are not so much 
given to erratic 
growth, but their 
fruiting wood is 
much more rapid 
growing than that 
of the Navel, and 
is apt the second or 
third year after 
planting to pro- 
duce a number of 
bare canes three 
or four feet long 
which, branching 
at the apex, be- 
come overloaded 
with fruit and 
break down. It is 
well to pinch these 
shoots and force 
them to branch be- 







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if i f 


x I '* 


k - 


gj 




Si % 

i 1 < 


- ■ ■( & m 


iff 




1 

Ml 




I ~..T 




- V 


■\ \ 


P6.. ^ 



Fig. 66. — Vigorous fruiting brush growing in 
the place of suckers. 



fore they grow too long. This should result in a stronger 
framework and render propping unnecessary in future 
years. 

As orange trees come into full bearing, the weight of 
fruit bends the lower branches down to the ground, with 



Pruning and Top-Working 213 

the result that uprights form upon them. All the up- 
rights which are of the fruiting type of growth should be 
allowed to remain. They may be depended upon to pro- 
duce a large proportion of the crop. Finally, however, the 
extremity of the lower mother branch becomes weakened 
with much fruiting, and, bending low under the young 
growth, becomes smothered. It should then be cut back 
to vigorous growth or removed altogether. 

In order that the short fruiting brush along the larger 
limbs shall produce a greater quantity of fancy inside fruit, 
it must have light. The top and sides of the tree are apt 
to get too thick and keep the center too dark. To prevent 
this, the wall of foliage should be opened up occasionally 
by taking out bodily a few small branches from various 
places in the walls and top. These holes will let in sun- 
light, which shifts as the sun moves across the sky. This 
is much better than outraging the tree by cutting out the 
entire top at one time. 

It is necessary to go over all bearing trees once in two 
years to remove all interfering and crossed limbs, as well 
as dead brush, and to thin the tops somewhat. The trees 
should also be examined several times each year, and any 
water-sprouts appearing on the trunk or main branches 
removed. 

PRUNING LEMONS 

Young lemon trees should be cut back severely from the 
beginning. They should be curbed in their riotous growth 
and forced to increase in size slowly and by the addition 
of the more or less crooked, much branched fruiting type 
of wood. The tendency of the lemon, and especially the 



214 



Citrus Fruits 



Eureka variety, is to throw out long 
branches which fruit at the ends. These 
bend over and are not only in the way of 
cultivation but are whipped about by the 
winds and often break with the weight 
of fruit. The main object should be to 
shorten back and strengthen the scaffold 
or main limbs in order that they may carry 
their load nearer the center of the tree and 
be stocky and stiff enough to withstand 
strong winds without swaying and thorn 
stabbing the fruit. This result is not 
always easy to attain. The tendency of 
lemon trees is to grow rapidly upward 
while most of the fruit is borne on more 
or less crooked horizontal branches. Ac- 
cording to the Baronio system, which is 
now practically abandoned, the trees were 
absolutely limited to horizontal growth 
after they had reached a height of about 
five feet. The vital trouble with this 
system was that it did not recognize that 
on deep, rich soil a lemon tree could not 
produce to its full capacity when limited 
to five feet in height. The tendency now 
is toward higher trees. With lemons at a 
high price it pays to climb after them, 
provided, of course, that the number 
borne near the ground is not reduced 

Fig. 67. — This 

extra vigorous orange shoot terminated at six inches with a fruit, show- 
ing that excess of food did not change it into a sucker. 



|L. ■ 


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lb 
w 


1 


mm 




11 

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- 


Ev : 

n 


Hi 


II 1 

flfw* 

■MI 


V 



Pruning and Top-Working 215 

by the presence of the high tops. It is the writer's belief 
that in deep, rich soil the economic limit of bearing 
surface of the lemon tree is not below ten feet. 

It is the custom of some growers to arbitrarily decide 
upon a certain height and then shear the tops to this line, 
making the trees appear from above as flat as a floor. This 
shearing process results in the brush quickly becoming too 
thick. It is much better to select those branches which 
reach above the line and cut them off at their junction 



Fig. 68. — A sixty-acre three-year-old Valencia orchard top-worked to 
lemons. The paper bags protect the buds from rose beetles. 

with the mother branch. If a vigorous upward growing 
shoot is cut back for a part of its length, it will put out 
several shoots which continue the growth. When build- 
ing up a young tree, this is necessary, in order to make the 
main branches more stocky, but it must always be followed 
by a thinning out of the resulting shoots. 

The following five statements are in the nature of 
maxims and should form the basis of any rational system 
of lemon pruning. They are accepted by the majority of 
lemon growers : 

a. Lemon sap flows more freely in vertical branches, 



216 Citrus Fruits 

hence vertical branches grow at the expense of lateral 
ones. 

b. A lateral crooked branch is much more fruitful than 
a straight upright one. 

c. Fruitfulness and high quality are the results of a slow 
but steady circulation of the sap. 

d. The finest quality fruit is borne on small fruiting 
brush on the interior of the tree and the sap supply of such 
brush should be protected from thieving suckers. 

e. The wider the angle the stronger the limb. Crotches 
with acute angles often split down. 




Fig. 69. — Fifteen months' growth on stocks shown in Fig. 68. 

Lemon trees may be pruned at any time of the year, 
but it is customary to defer removing large limbs till the 
time when there is the least amount of fruit on the trees. 
This usually is in the late spring. Some of the larger 
ranchers employ pruners, for the mature trees, who work 
the year round. They confine their work to thinning out 
the fruiting brush, removing interfering and broken 
branches and suckers from the trunks. In addition to 
this a special group of pruners go over the trees each 



Pruning and Top-Working 217 

spring and autumn and cut out the superabundant growth 
of vegetative shoots in the tops. 

When it is necessary to cut off large limbs containing 
some good fruit, it is wise to pick this fruit from the limbs 
at once. If this is not done, the leaves (being separated 
from the roots) will draw on the water contained in the 
juice of the lemons and dry them out very quickly. 

DISPOSITION OF PRUNINGS 

If prunings are to be hauled out and burned, they 
should be removed to some distance. Citrus trees are 
extremely susceptible to injury from the heat of fires. 
However, in a country such as California where humus- 
forming materials are scarce, it is very wasteful to burn 
prunings. They should by all means be chopped up fine 
and plowed into the soil. On several of the larger ranches 
power cutters run by gasoline engines are drawn through 
the orchards, the prunings being chopped up and allowed 
to lie where they fall till succeeding cultivations gradually 
work them into the soil. On other ranches the prunings 
are cut up with hand shears. 

PRUNING FROSTED TREES 

When citrus trees are injured by frost, it is wise to defer 
pruning several weeks or until it is perfectly clear just how 
far back the wood has been killed. After the line of de- 
marcation between living and dead wood becomes appar- 
ent, no time should be lost in taking the necessary steps 
toward reconstructing the top in the best way with the 
least possible loss of time. 



218 Citrus Fruits 

The problems involved in mending and reforming the 
tops of frosted citrus trees fall naturally into two classes : 
those having to do with very young trees and those con- 
cerned with large mature trees. 

Reheading Young Trees 

When a one- or two-year-old tree has been killed to a 
point near the ground it should first be determined in each 
individual case whether the dead wood extends below the 
bud union. If there remains enough live wood above the 
union to grow a strong shoot, such a shoot may be allowed 
to grow and become the trunk of the new tree, all other 
shoots being suppressed. If on the other hand the trunk 
is killed below the union, it will be necessary to set a new 
bud. The opportunity is thus presented of reconsidering 
the relative profits to be derived from oranges, lemons, or 
pomelos. In case the root is sweet orange the bud may be 
set immediately, provided there is sufficient room to do so 
without excavating the soil, for in no case should a bud be 
set below the soil. In case the trees have been killed 
to the ground it is well to select the most vigorous sprout 
and bud into this two or three inches above the ground. 
If the root is sour orange or pomelo, it is best to place the 
bud six or eight inches from the ground on a strong sprout. 
This will result in a somewhat hardier tree and one more 
resistant to gum-disease. 

In all cases in which a new trunk must be grown on trees 
already planted in orchard form, it is necessary of course 
to stake the trees and tie them every few inches, taking 
care to disbud often and remove all sprouts from the root, 



Pruning and Top-Working 219 

eventually heading the tree at the desired height. A 
stake larger than the customary building lath is advisable 
in order to prevent injury by passing teams and tillage tools. 

When the tops of young trees are partly frozen it will be 
found, especially with lemons, that the more rapid grow- 
ing upright shoots have been killed, while the fine fruiting 
brush has been spared. Instead of cutting back all these 
injured shoots in proportion to the injury, it is much better, 
especially with lemons, to take out most of the very strong 
upright canes entirely. If they are merely cut back and 
allowed to remain, each one will throw up several shoots, 
which in turn must be cut back, the final result being a 
broom-like growth with far too many shoots. The proper 
pinching and thinning of such a multiplicity of shoots will 
involve much more labor than the commercial orchardist 
can afford. It is better, therefore, to remove most of the 
upright vegetative shoots entirely and rely on new shoots 
from the horizontal wood to enlarge the framework of the 
top. All water-sprouts arising from the trunk and around 
the crotches should be vigorously suppressed. It is a good 
plan to whitewash the exposed trunks in order to prevent 
sunburning of the bark. 

It often happens that the bark of the trunks of young 
trees will be split by the frost and will dry out, resulting in a 
strip of dead bark on the southwest side. This condition 
is not necessarily serious, provided there remains a strip 
of live healthy bark of sufficient width to provide a flow of 
sap to the top. The living bark will gradually increase 
in width and extend over the dead areas, in time covering 
them entirely. In order to prevent the entrance of wood- 
decaying fungi it is well to paint the dead areas with white 



220 Citrus Fruits 

lead, asphaltum paint, or bordeaux paste. Bandaging is 
often resorted to in order to prevent the injured bark from 
drying away from the wood. Experience has shown that 
this is of little value unless it is done immediately or within 
a few hours after the injury. On a large acreage it is im- 
practicable. 

Reheading Mature Trees 

Orange trees are much more resistant to frost than lemon 
trees. Over certain large areas the freeze of January, 1913, 
ruined the fruit and completely defoliated the trees without 
killing back the wood to any appreciable extent. In 
such a case, the trees need no extra pruning, although 
while the leaves are absent a good opportunity presents 
itself to remove conflicting branches and thin the brush 
with greater ease and efficiency than is possible when the 
trees are covered with leaves. 

Where the wood is killed back to any extent, however, 
too many shoots are apt to start from the live wood and 
many suckers appear about the crotches . Theoretically the 
shoots should be thinned out, leaving only what is needed. 
Those left will be stronger and bear more fruit than if such 
a large number were allowed to struggle for life. Practi- 
cally, however, such a course would require more labor 
than is available and large growers will have to adopt 
the next best course, namely, that of cutting out all the 
dead wood and thinning the new growth by taking out 
bodily a certain number of branches. 

Where lemon trees have been killed back severely, it 
is best to withhold or decrease the fertilizer during the 
succeeding year in order that a more moderate growth 



Pruning and Top-Working 221 

may take place. Frozen trees have been thrown out of 
balance. They have the same amount of root as before, 




Fig. 70. — Three-year-old Navel head on top-worked sweet seedling. 

which is now pouring sap into a much reduced top. The 
result is bound to be a tremendous new growth breaking 
out all over the trunk and branches. At best a great deal 



999 



Citrus Fruits 



of labor will be required to properly sucker the trees. If 
additional stimulation is brought about by the application 
of quick-acting fertilizers, this trouble will be increased. 
Wise lemon growers prefer to build the new head out of 
the more moderate growth of fruiting wood rather than 
out of water-sprouts. It is not necessary or always ad- 
visable to root prune frosted trees, but if hardpan or plow- 
sole exist, it may be broken up with a subsoil plow at this 




Fig. 71. — Pruning a frosted lemon orchard. 

time with less injury to the trees from cutting large 
roots. The number of roots which may be cut with 
impunity will of course depend upon the amount the tops 
of the trees have been killed back. 

It seems reasonably certain that no injury to the tree 
can result from any of the materials passing from the 
frozen oranges back into the tree. An examination of 
those oranges which have been too badly frozen to be fit 
for shipment shows that most of them have been only 
partially killed ; consequently they are presumably re- 



Pruning and Top-Working 223 

spiring carbon dioxide. This loss of energy would be saved 
if the oranges were removed from the tree rather than al- 
lowed to hang all summer. There is no experimental 
evidence, however, to show whether this loss is sufficient 
to warrant the cost of early removal by hand. In case the 
fruit is picked off the trees it may safely be plowed under, 
thus adding humus and some plant-food to the soil. 
There is no danger of the soil becoming acid as a result 
of this practice, for in some orchards cull lemons and 
oranges are regularly used in large quantities as a manure 
with only beneficial results. 

TOP-WORKING OLD TREES 

It often becomes desirable to change an orchard from 
one variety to another by top-working. Any variety 
of citrus tree may be top-worked to any other variety, 
although some combinations succeed better than others. 
It is thought that Valencia oranges do not always do well 
when worked on lemon. Satsuma, as a rule, should not 
be worked on sour orange. 

There is no particular difficulty in regard to this process 
except that it interferes with the production of the or- 
chard and much time is lost during the transition from one 
variety to another. 

Top-working may be accomplished in any one of three 
ways : 

1. By cutting off the entire top and budding directly 
into the trunk or large limb stubs. 

2. By cutting the top back to large stubs and allowing 
strong shoots to grow, and later budding into these shoots. 



224 Citrus Fruits 

3. By cutting back the top to small stubs and budding 
directly into these. 

This last method entails so much labor and trouble 
in keeping water-sprouts down that it is little used except 
for highly prized dooryard trees. 

Some growers cut the entire tops off as soon as the buds 
have taken ; others leave a few branches to draw the sap 
by the buds. " Safety branches," as they are called, pre- 
vent the buds from being " drowned out " and should 
be left when top-working is done in late spring or summer. 
Some growers cut away a few limbs a few months before 
budding in order to cause the old bark to slip better. 
The thick heavy bark of old limbs or trunks should be 
scraped down thin immediately surrounding the bud at the 
time it is set. Large buds should be used and in many 
cases they take better if the bit of wood which is severed 
with the bud is removed, thus bringing together larger 
areas of cambium. 

After the buds have begun to grow, great care should 
be taken not to allow any sprouts from the old wood to 
grow up and crowd them out. In some cases, as when 
lemon is worked on orange, it is easy to tell stock from 
scion, but when two varieties of lemon or orange are 
worked together, it soon becomes very difficult to tell 
which is stock and which is scion. On account of this 
difficulty, and for other reasons, the top-working of old 
orchards is practiced to a much smaller extent now than 
formerly. 

When an old orchard is top-worked, the trunks should 
be protected by whitewash or sacking, for sunburn will 
be almost sure to result from the exposure of the bark. 



Pruning and Top-Working 225 



PRUNING TOOLS 

The operation of pruning involves the making of wounds ; 
and since these wounds heal over quickest when the cut 
is smooth and even, it follows that any tools which crush 
or tear the bark are objectionable. For all small branches 
and twigs, a strong sharp knife is ideal. It is a fact, how- 
ever, that for economy's sake, some form of hand shears 
with one blade and a guard are universally used in com- 
mercial orchards. For larger branches the two-handled 
lopping shears are most convenient. For removing large 
limbs, a saw is necessary, but the pruning saw with teeth 
on both edges should be avoided, as it is too difficult to use 
without damaging the tree. By far the best saw for use 
in a citrus orchard is that known as the "California" 
pruning saw (Fig. 63) with reversible and detachable 
blade. The blade of this saw may be turned in any direc- 
tion, and it is especially convenient for work in close 
places. It is very important to keep all pruning tools 
sharp. A half dozen extra saw blades should enable the 
pruner to keep a sharp, well-set saw in hand at all times. 

A satisfactory outfit for the citrus tree pruner may be 
enumerated as follows : 

1. A short, light stepladder. 

2. One pair strong leather gloves. 

3. One pair hand shears (Henckel's special No. 9 pre- 
ferred). 

4. One California pruning saw (six extra blades). 

5. One B. & H. special pruning saw. 

6. One pair lopping shears with riveted wooden handles. 

7. Bucket of paint with brush for dressing large wounds. 



226 Citrus Fruits 



WOUNDS AND DRESSINGS 

All large limbs should be sawed off close to the trunk 
or mother limb in such a way that new bark will grow over 
the cut surface from all directions. This takes place most 
readily when the cut surface is parallel to the mother limb. 
Stubs are a source of danger to the tree and reflect dis- 
credit upon the orchardist. When a sucker is cut off and 
even a very short stub left, other suckers will put out from 
the same point until there is formed what is known as a 
" sucker-nest." This is very objectionable, and when such 
" sucker-nests " are found in old trees they should be re- 
moved cleanly with one cut of the saw, going well into the 
wood in order to stop any further growth of suckers from 
that point. 

It requires several years for a large wound to heal over 
entirely, and during this time it is susceptible to infection 
by various fungi which cause the wood to decay. The fine 
checks in the wood which form as the wound dries, are 
ideal lodging places for the spores of decay-producing or- 
ganisms. Decay often slowly works its way back into the 
trunk and causes hollow center. Decayed wood in the 
heart of a tree weakens it and brings on a diseased condi- 
tion. Fortunately it is a simple matter to prevent this by 
disinfecting the wounds and applying some dressing which 
will protect the exposed wood while it is healing over. 

In the case of pruning-wounds where small limbs are re- 
moved it hardly pays to go to the expense of disinfecting 
the wounds before the dressing is applied. In tree surgery, 
however, where large cavities are chiseled out and where 
large limbs are removed, it is well to apply a coat of liquid 



Pruning and Top-Working 227 

creosote to sterilize the wound and after this has dried 
the waterproof dressing may be used. 

The matter of complete covering is of the utmost 
importance. Wound dressings should exclude the air and 
render the cut surface impervious to water. As infection 
may take place through a very small opening, time and 
labor are entirely wasted unless the wounds are com- 
pletely covered. 

A large number of substances which vary widely as to 
cost and convenience of application are used for dress- 
ing wounds. As a rule those which require heating be- 
fore application are not to be recommended, because it is 
too much trouble to carry a portable fire in the orchard, 
and the hot sun in summer is apt to cause them to melt 
and leave the wound. Out of a large number of formula? 
three have been selected for mention here. No. 1 is satis- 
factory for small jobs in yards and gardens, but is much 
more expensive than No. 2, which should be used in all 
large orchards : 

No. 1. Alcohol 6 oz. 

Turpentine 1 oz. 

Tallow 2 oz. 

Rosin 1 lb. 

Heat the tallow and rosin together, cool slightly, and add 
alcohol. Then stir in the turpentine. This may be used 
cold. 

No. 2. Asphaltum paint. Heat the asphaltum till 
thoroughly melted and, after removing to a safe distance 
from fire, dilute with benzine to make a mixture which 



228 Citrus Fruits 

when cold is of the consistency of thick paint. As the 
asphaltum varies greatly in density, no definite proportion 
of benzine to asphaltum can be stated. Asphaltum tree 
paint may be bought in cans already mixed, but is much 
more expensive in this form. 

When on account of gum-disease, wind breakage, top- 
working, or other reasons the trunks of old trees are exposed 
to the sun, they should be protected with a coat of tree 
whitewash or bordeaux paste or No. 3. 

No. 3. f 1 lb. copper sulfate or Milestone 

| 3 qt. water 
, | 2 lb. quick lime 
[ 3 qt. water 

Solutions a and b should be prepared separately before 
being mixed together. 

Tar is often recommended as a wound dressing, but coal 
or gas tar should be avoided, as it usually contains com- 
pounds which are injurious to the bark of citrus trees. 
Most of these injurious compounds are volatile and may 
be driven off by boiling the tar, but even the boiled tar 
has no advantage over the asphaltum paint. 

Small cuts heal over quickly and are usually so numer- 
ous that it would hardly pay to apply the dressing. Ordi- 
narily cuts less than one inch in diameter are not dressed 
unless they are conveniently situated. 

Often in old neglected orchards trees will be found in 
which decay has worked its way back into the wood of the 
trunks. The proper treatment of such cases involves 
tree surgery, the methods of which have been well de- 
scribed and illustrated by J. F. Collins in the United States 



Pruning and Top-Working 229 

Department of Agriculture Yearbook for 1913, pages 163 
to 190. It is necessary of course to remove all of the de- 
cayed and discolored wood by means of suitable tools 
such as chisels and scrapers. After the cavity has been 
carefully cleaned out it should be sterilized with creosote 
and then given a coat of asphaltum paint. The cavity 
may then be filled with cement (1 part of cement to 3 of 
sand). It is necessary to undercut the cavity somewhat 
after the fashion of a dentist preparing a cavity in a tooth, 
in order that the block of cement may be held in place. 
Sometimes nails are driven in large cavities for the same 
purpose. After the cement has hardened the whole 
job should be painted over and thoroughly waterproofed. 
It is wise to inspect such work at least once a year and re- 
paint if not entirely waterproof. 

If properly treated, such cavities will heal over in a few 
years and the tree will be saved and greatly strengthened. 

It is a common thing for the main branches of old lemon 
trees which have been improperly headed to split down 
under the load of fruit. Such branches may be saved for 
many years of usefulness by bolting. Auger holes should 
be bored directly through the trunk and large iron bolts 
with washers used. It is important in such cases also to 
carefully disinfect the wounds made, and dip the bolts 
and washers in bordeaux paste before inserting. On ac- 
count of prevalence of the gum-disease organisms and the 
ease of inoculation disinfection is especially important. 
The cracks in the trunk should be filled with bordeaux 
paste before they are drawn together. The bolt heads 
and the exterior of the cracks should be given a coat of 
asphaltum when the work is complete. 



q*HAPTER XIV 

FROST AND ORCHARD HEATING 

Perhaps no phase of citriculture has advanced with 
more rapid strides during the last few years than orchard 
heating. For hundreds of years in certain parts of Europe 
some protection to vineyards and gardens has been se- 
cured in a crude way by smudging. The modern science 
of orchard heating as practiced to-day, however, has been 
developed within the past fifteen or twenty years. More- 
over this subject is of such vital interest to every citrus 
grower that it is considered well worth while to discuss the 
matter more or less in detail. 

HISTORICAL COLD PERIODS 

In Blodget's " Climatology," published in 1857, we find 
mention of a cold period as early as 1748 which caused con- 
siderable damage to the tropical fruits of the South. 
Other cold periods occured in Florida in 1766, 1780, 1800, 
1835, 1852, 1876, 1886 ; and in 1894-95, the memorable 
double freeze occurred which almost wiped out the citrus 
orchards of Florida and changed the geography of the 
citrus industry there. Cold periods may therefore be ex- 
pected to recur at intervals of about twenty years. 

230 



Frost and Orchard Heating 231 

In California the available records do not extend so far 
back. In 1882 a severe freeze was experienced, a mini- 
mum of 21° F. being registered at Fresno. Ice was 
formed in Los Angeles, and the surrounding hills were 
covered with snow. Other cold periods occurred in 1888, 
1891, 1895, 1899, 1911, and 1913. Frosts occur in Cali- 
fornia at average intervals of five or six years. Fortu- 
nately California has not so far experienced a frost ap- 
proaching in severity the one which visited northern 
Florida in 1894-95. It should be pointed out, however, 
that the great damage in Florida was not due so much to 
the severity of the frost as it was to the peculiar relations 
of the two cold periods. The first denuded the trees of 
foliage and fruit and was followed by a period of warm 
weather. When the new growth was pushing vigorously 
and the tender shoots were about four inches long, the 
second freeze came and killed the trees to the ground. 

The freeze of January, 1913, was the most damaging in 
the history of California, and in the southern part of the 
state the temperature was lower than had been known for 
a period of sixty years. Heavy frosts occurred on Janu- 
ary 4, 5, 6, 7, and 8. Strong winds preceding the frosts 
came from the north and northwest rather than, as usu- 
ally happens, from the northeast. The wind began to 
blow shortly after noon on January 4, and continued until 
3 a.m. on January 6. Instead of the usual draught through 
Cajon Pass at an elevation of 3823 feet, the winds came 
directly over the Sierra Madre Range, whose elevations 
exceed 6000 feet. During the midday hours on the 4th, 
5th, and 6th, the temperature did not rise much above 50° F. 
and in some places did not reach 50° F. Apparently the 



232 Citrus Fruits 

whole mass of air, to an elevation of several thousand feet, 
was at a low temperature. The wind was extremely dry. 

During this freeze the fruit was subjected to tempera- 
tures below freezing for four successive periods, averaging 
four hours for the first, thirteen hours for the second, 
thirteen hours for the third, and nine hours for the fourth. 
In all, during a total period of 72 hours, during which, 
under normal conditions, the trees would have received a 
supply of heat approximately represented by 1500 hour- 
degrees, starting from a temperature of 40° F., they only 
received 220 hour-degrees. There were 170 hour-degrees 
below freezing, and of these 50 were below 25° F. 

Minimum temperatures of 13° were recorded at Escon- 
dido ; 16° at Chino ; 17° at Pomona; 18° at Redlands; 
21° at Riverside and Pasadena; and 25° at San Diego. 

This cold period destroyed at least ten million dollars' 
worth of fruit, to say nothing of the damage to the trees. 
Yet the industry recovered very quickly, and in 1913-14 
the normal amount of fruit was marketed. During this 
trying period the practical value of orchard heating was 
clearly demonstrated. Orange growers who w T ere properly 
equipped saved their crops, and lemon growers also saved 
their crops and trees and in some cases marketed sufficient 
fruit the following summer at very high prices to pay the 
entire cost of their heating equipment several times over. 

With deciduous fruits, the damage is done by late spring 
frosts which occur after the trees have blossomed. It is 
only necessary therefore to be prepared for orchard heating 
during a few weeks in March and April. With citrus fruits, 
however, it is very different. The fruit hangs on the trees 
all winter, and it is necessary to be prepared to heat the 



Frost and Orchard Heating 233 

orchards at any time between November 15' and March 15 
or for a period of four months. 

FORECASTING FROSTS 

There are several ways by which plants lose their heat. 
When two bodies at different temperatures are in contact, 
they tend to become alike in temperature by the direct 
conduction of heat from the particles of the warmer body 
to those of the cooler. Thus it is that the earth and living 
plants upon it, having become warmed by the sun, lose part 
of their heat to the atmosphere lying directly above them, 
through this process of conduction. This heat is con- 
ducted slowly upwards in the air. Air, however, is a poor 
absorber and conductor and would become warmed only 
very slowly were it not for another process of greater im- 
portance which soon begins to act. 

Air, like all other gases, expands and becomes lighter 
upon heating. Therefore, the air at the surface of the 
earth which has become heated by conduction, rises, and 
its place is taken by the colder air from above. A kind 
of circulation is thus set up, somewhat resembling that in 
a vessel of water which is being heated. 

In the horizontal movements of the air, which we call 
winds, the process of convection also comes into play. 
When a cold wind is blowing, as every one knows, the 
heat of exposed bodies will be rapidly carried away. 

By still another means is the heat of the earth and trees 
lost to the air above. It is expended in the process of 
evaporating moisture from their surfaces. The heat 
thus lost is commonly said to have been changed into 



234 Citrus Fruits 

latent heat ; it is really not heat at all in this latent con- 
dition, but is simply the energy needed to overcome the 
intermolecular attractions of the evaporating substance. 
Evaporation may be of considerable importance in lowering 
the temperature of vegetation, especially when the air is dry. 
But the three processes just mentioned are by no means 
sufficient to account for the tremendous loss of heat which 
occurs on a quiet, clear night when freezing temperatures 
are most likely to occur. The fourth and much more 
important way by which heat is lost is by that peculiar 
process known as radiation. By this process the vibratory 
heat motion of a body is transferred in part to the ether, 
setting up in it waves which proceed outward along straight 
lines and in all directions, in the same manner that sound 
waves emitted by a vibratory tuning-fork proceed out- 
ward in all directions through the air. The surface of the 
earth is continually losing heat by radiation into space; 
but during the day it usually receives heat more rapidly 
from the sun than it loses it by radiation, and therefore 
it grows warmer. At night, however, when the sun's 
heat is cut off, the effect of loss of heat by radiation is not 
counterbalanced and the earth's temperature conse- 
quently falls. Radiation takes place more rapidly from 
the surface of plants than it does from the air about them, 
so that, on still nights, these surfaces are frequently cooled 
several degrees below the temperature of the surrounding 
air. 

Factors influencing the Occurrence of Frost 

Wind, relative humidity, and absence of clouds and dust, 
all influence the occurrence of frost. On still nights the 



Frost and Orchard Heating 235 

air as it cools arranges itself in strata, the coldest and 
heaviest next the ground. Wind tends to mix the air and 
bring it all to the same temperature, which of course 
would mean an increase in the temperature of that next 
the ground which is in contact with the plants. 

Atmospheric moisture lessens cold in two ways : first, 
it retards the escape of the day's heat by radiation at 
night; second, the latent heat of the vapor becomes 
sensible heat when the condensation of the vapor takes 
place. The indirect influence of the water vapor in the 
air, in checking radiation from the earth, is a powerful 
conservator of heat. 

When moist air is cooled, it will finally reach a 
temperature of saturation which is known as the " dew 
point," when no more water vapor can be held at that 
temperature. When cooled further, water will be de- 
posited as liquid drops (dew) if the temperature is above 
freezing point, or as ice crystals (frost) if below the freez- 
ing point. Now, when water vapor is changed into 
liquid form, a large amount of heat is liberated — the 
same amount which is required to change the same 
quantity of water into vapor. This liberated heat be- 
comes available to warm the air. It is said that the 
precipitation of one quart of dew will liberate enough 
heat to raise the temperature of 1000 cubic feet of air 
25° F. 1 

Clouds also have a marked influence in preventing the 
escape of heat from the earth; they reflect or radiate 
back to the earth the heat which escapes from it. There- 

1 W. H. Hammon, "Protecting Orchards Against Frost," 
Bui. No. 70, California State Board of Horticulture, 1896. 



236 Citrus Fruits 

fore, frosts, as a rule, do not occur on cloudy nights, and 
the clouding up of the sky during the evening may often 
prevent expected frost. Dust and smoke suspended in 
the air act in much the same way as clouds. 

The conditions favorable for a freeze may then be 
summarized as follows : 

1. A clear sky; thus furnishing no check to loss of 
heat from the earth and trees by radiation. 

2. Dry air; because cooling by radiation will then 
continue to a much lower temperature before being 
checked by the heat liberated in condensation. 

3. Still nights; because the air, not being mixed by 
the wind, arranges itself in layers according to its density, 
with the colder, heavier air beneath in contact with 
vegetation. 

4. Very cold dry north winds which abate before dawn. 

5. A comparatively smoke and dust free atmosphere. 

Local Conditions affecting Frost 

Practically every citrus district in California has its 
frosty and its frostless spots. Even on the same ranch 
the line is often clearly drawn between safe and dangerous 
ground. There are several reasons for this. In the first 
place it is well known that frost is less likely to occur at 
moderate elevations, or on low hillsides, than in low-lying 
valleys and depressions. This is caused by what is 
known as " inversion of temperatures." On a hillside or 
bench land with good slope, the air, as it cools and grows 
heavier, will flow quietly downward and collect in the low- 
lands, thus crowding the warmer air upward. This warm 



Frost and Orchard Heating 237 

air floating on top spreads out to the hillside, to which 
it imparts a portion of its heat. And so a gentle but 
complex circulation is kept up which accounts for the 
warming of one spot or belt and the cooling of another. 
Often there are unknown local factors influencing this 
circulation which makes it very difficult to foretell on 
any given hillside just where the thermal belt will be. 
This is clue no doubt to various unseen cross-currents 
caused by the irregularities of the mountains. Again, a 
valley is usually shaded for a longer period, both in the 
morning and afternoon, than all the uplands ; therefore 
it goes into the night with a less store of heat with which 
to counteract freezing temperatures. 

The type of frost just described is the normal kind 
experienced in Calif ornia and is known locally as a " gravity 
frost." This type of cold weather is comparatively easy 
to combat with orchard heaters. Occasionally, however, 
the conditions are reversed, as was so well exemplified in 
the ''blizzard" of January, 1913. During this period 
the cold north wind sweeping directly down from over 
the mountain tops, 6000 feet in height, caused the trees 
on the uplands or thermal belts to suffer more severely 
than those planted on lower land, as were the orchards of 
Orange County. 

Conditions indicating Frost in California 1 

The condition preceding frost in California is indicated 
by the passage of a low barometer area from Idaho south- 
adapted from A. G. McAdie's "Frost Fighting," U. S. 
Weather Bureau, Nos. 29 and 219. 



238 Citrus Fruits 

ward across Utah, thence westward into southern Nevada, 
and finally southward into southern California. For the 
most part, frosts are due to the movement of cold air 
from the northeast. Frosts also occur when a low 
area over southern California moves rapidly southeast 
and is followed by a high wind from northern California. 
Conversely, when the air moves from the sea inland, there 
is little danger from frost. 

The topography of southern California favors drainage 
of the air from the mountains seaward at certain hours, 
and a return movement of the surface air inland at cer- 
tain hours. Thus conditions are highly favorable for the 
formation of air streams, which reverse their direction at 
least twice in each 24-hour period. 

In general, the lower air flows to the southwest during 
the night and early morning, and to the northeast during 
the afternoon. During the winter months, when areas 
of high pressure pass over the Great Basin, the surface 
air apparently moves south, crossing the northern flank 
of the Sierra Madre and descending with some momentum 
into the Great Valley. The wind movement is particu- 
larly marked in the vicinity of mountain passes. 

During these so-called " northers," the temperature 
rises and the humidity falls. The existence of a low 
pressure area south of the Colorado seems to intensify 
this condition. Heavy frosts occur, as a rule, after a 
period of high north winds, and are traceable to the dis- 
placement of the warm air in the valley by cooler, very 
dry air. This dry air permits very rapid radiation, and 
when the wind lulls, which is apt to occur after sunset, 
the drop in temperature is very rapid. 



Frost and Orchard Heating 



239 






HOW PLANTS ARE INJURED BY COLD 

In the U. S. Department of Agriculture Yearbook for 
1895, B. T. Galloway describes what takes place when 
plant tissues freeze, very concisely as follows : 

" All the phenomena involved in the freezing of succu- 
lent and other plants depends on the condition of the 
protoplasm or living matter in the plant cell. If the 
temperature is suffi- 
ciently low to cause 
a chemical disorgan- 
ization of the living- 
substance, the part 
of the plant where this 
takes place dies. If, 
on the other hand, no 
actual disorganiza- 
tion of the cell con- 
tents occurs, the af- 
fected parts may 
recover. It is hardly 
necessary here to en- 
ter upon a discussion 

of the various phenomena. Suffice it to say that 
under the influence of cold the water in the cells 
escapes, and may be frozen either in the spaces 
between the cells or on the surface of the leaf, stem, 
or whatever the part may be. As the temperature 
rises this frozen water may again be taken up by the 
cells, and in such cases little or no injury results. If for 
any reason, however, the cells are not able to regain the 



-3> 




A B 

Fig. 72. — A, normal vesicles of lemon; 
B, enlarged vesicles from frosted fruit, 
six months after injury. (Nat. size.) 



240 Citrus Fruits 

water withdrawn by" the cold, injury or even death may 
result. In many cases the rapidity with which the ice is 
thawed has a marked effect on the ability of the cells to 
regain their normal condition. If the thaw is gradual, 
the water is furnished no faster than the cells can absorb 
it, and equilibrium is therefore soon restored, the chemical 
processes which were checked during the freeze are re- 
sumed, and the plant soon regains its normal condition. 
With a rapid thaw, however, the cells are not able to take 
up the water as fast as it is furnished, and as a result 
chemical decomposition sets in and death follows. Death 
in this case is essentially the same as that which results 
from drought. The cell loses water to such an extent 
that it is not again able to become turgid, and as a result 
it finally withers and dies." 

That the above is equally true in the case of citrus 
fruits has been shown by Bioletti. 1 " Frozen and un- 
frozen oranges from the same tree were received — with 
the request to determine whether the cells of the frozen 
oranges had burst and whether this was the cause of the 
rapid drying up of the frozen fruit. Microscopic exami- 
nation showed no difference in the cells of the two kinds. 
Pieces of the flesh of both kinds were placed in a water 
solution containing 33 per cent of cane sugar, and other 
pieces in distilled water. The next day the cells of both 
kinds in the sugar solution had shrunk equally, while 
the cells of those in distilled water had swollen equally ; 
indicating that there were no breaks in the cell walls of 
the frozen oranges." 

The condition of the plant, whether in a period of 

1 California Agr. Exp. Sta. RpL, 1897-98, p. 184. 



Frost and Orchard Heating 



241 



succulent growth or in a 
dormant state at the time 
of low temperature, has an 
important bearing upon 
the limit of desiccation of 
the individual cell, dormant 
plants being able to with- 
stand lower temperatures 
than those growing rapidly. 

The moisture from the 
cells of frozen oranges either 
evaporates through the 
rind or passes out through 
the stem and is transpired 
by the leaves. The tissues 
of frosted fruit usually bear 
small white specks of hes- 
peridin, evidently formed 
by chemical changes. The 
surface ordinarily shows 
very little indication of 
injury, although the inside 
tissues may be dry and 
shrunken. While frozen 
citrus fruits may occasion- 
ally be bitter in taste, no 
injury has ever been known 
to follow their use even 
when eaten in large quantities. 

Leaves of citrus trees which have been frosted at first 
curl up ; they may remain upon the tree and recover to 




Fig. 73. — Bark on fruiting brush 
of lemon split by frost. 



242 Citrus Fruits 

a certain extent, or fall off after a few days. Defoliation 
may occur without serious injury to the smaller branches. 
The injury to branches naturally depends upon the degree 
of dormancy and the diameter of the branch ; the twigs 
and smaller branches may be cut back seriously by frost 
without any appreciable injury to the larger parts. A 
very common form of frost injury to young trees is the 
splitting of the bark along the trunk and lower branches ; 
the cracks are often noticeable a day or so after the frost, 
and if badly injured, the edges continue to roll back, ex- 
posing the bark and wood to the weather. 

The amount of cold a citrus tree will endure without 
injury will depend upon: (1) the kind of tree; (2) the 
degree of dormancy of the tree ; (3) the length of time the 
cold lasts ; and (4) the kind of weather following the cold. 
Citrus trees resist frost in the following order, beginning 
with the hardiest : trifoliate, sour or Seville orange, Sat- 
suma mandarin orange, kumquat, sweet orange (such as 
the Navel), pomelo, citron, lemon, and lime. In general 
it may be said that oranges, if fairly dormant, will endure 
a temperature of 25° or 26° F. for an hour or so without 
injury. Below 25°, the fruit begins to freeze, first 
that on the outside of the tree and near the ground, and 
later the inside fruit. At 20 to 22° F., the twigs begin 
to die back and the leaves fall, while a temperature of 
17° or 18° for four or five hours, unless the trees are quite 
dormant, will kill them back to branches two or three 
inches in diameter. Lemons are much more tender, the 
fruit being injured at 26 to 28°. The limes are very 
tender, being killed back considerably at 28 to 30°. It 
must be understood that these figures are approximate 



Frost and Orchard Heating 243 

only, a large number of variations being noted in many 
localities. 

PREVENTION OF FROST INJURY 

Very many schemes have been evolved from time 
to time for protecting orchards from frost. Let us 
briefly consider a few of the most important. 

1. By selection of frostless or nearly frostless locations. — 
This plan is practicable for the few who are so fortunate 
as to possess frostless sites. The great majority of citrus 
orchards, however, are so situated as to be subjected to 
occasional low temperatures. It was pointed out in 
Chapter II that the best commercial oranges were pro- 
duced, not in tropical climates, but very near the frost 
line. It is to be expected, therefore, that as the citrus 
plantings crowd close to the variable and uncertain frost 
line, that the frost problem will always be with us. 

2. By planting resistant varieties or grafting on resistant 
root-stocks. — As a rule, oranges are planted in the colder 
spots and lemons in the warmer, but as has been pointed 
out, in time of blizzards the lines established by gravity- 
frosts are blotted out and all the orchards may experience 
low temperatures. Much has been written in Florida 
about the extra hardiness gained through the use of 
the trifoliate root-stock. Whatever may have been the 
experience in Florida, experiments have shown that in 
California nothing is to be gained by the use of this 
stock. At the Citrus Experiment Station at Riverside 
there is a duplicate root-stock experiment, one part of 
which is on high ground and the other on low. These 
trees have been examined critically after the severe frosts, 



244 Citrus Fruits 

and all who have seen them agree that the trifoliate root 
does not augment the hardiness of the scion grown upon it. 

3. By breeding new frost resistant forms of citrus. — ■ 
Directly after the Florida freeze of 1894-95, Messrs. 
Webber and Swingle began experiments in breeding more 
hardy citrus fruit. This was accomplished by hybridizing 
the various edible forms with the trifoliate orange, and 
the citranges described in Chapter IV were thus produced. 
As yet, however, none of these hardy forms have proven 
of commercial value, they being used only for domestic 
purposes. Breeding new fruits is a very slow process, and 
time alone can tell what the final results may be. For 
the present, they offer no opportunity to the commercial 
grower. 

4. By the use of various mechanical devices designed to 
conserve heat by checking radiation. — Much good may 
be accomplished by the use of screens of various sorts 
in conserving latent heat. Such methods are well 
adapted to young trees during gravity-frosts. When the 
blizzard comes, however, chilling the earth and trees and 
blowing the heat out to sea, there is but little latent heat 
left in the plants to conserve, and such methods are entirely 
inadequate. 

The lath screens used over seed beds as described in 
Chapter V not only temper the rays of the sun, but serve 
as a protection from ordinary frosts as well. 

Such screens have been tried over large commercial 
groves but proved too expensive and cumbersome. Sheds 
over bearing groves have been abandoned in California. 

Newly planted trees are much more susceptible to frosts 
than old trees, and it is a very common practice to pro- 



Frost and Orchard Heating 



245 



tect them during the first two winters by tying them up 
in cornstalks or tulles. 

Cloth screens have been used to some extent over both 
nursery stock and old groves. The netting cloth which 
is used over tobacco fields in Connecticut has been tried 
and found to give some protection, although just how much 
is not yet definitely determined. Sheets of burlap or tent 




Fig. 74. — Three-year-old trees protected with cornstalks. 

cloth may be used to advantage in protecting specially 
tender or valuable trees" in dooryard and garden. When 
the cold is severe, a lighted lantern may be set under the 
tent. 

In northern Florida it is a common practice to make a 
mound of earth around young trees to protect the bud 
union and prevent the necessity of having to rebud the 
trees. Under California conditions this is dangerous on 
account of the prevalence of the gum-disease organism 



246 



Citrus Fruits 



in the soil. If trees are mounded in California, the trunks 
should be first painted with bordeaux paste and then 
tied with cornstalks in such a way as to prevent the earth 
coming in contact with the bark of the trunk. 

5. By raising the dew-point by the addition of water 
vapor to the air. — This is accomplished in various ways 




Fig. 75. — Screens of tobacco cloth as a frost protection. 

such as burning large quantities of wet straw, distributing 
steam among the trees, filling the air with spray such 
as by overhead irrigation, and by ordinary irrigation. 
Burning wet straw has been found of no avail for two 
reasons. There is not enough straw available in a coun- 
try where every scrap of organic matter is needed for 
increasing the humus content of the soil. In the second 
place the air is so dry in California that it is often too 



Frost and Orchard Heating 



247 



big an undertaking to attempt to raise the dew-point, 
especially when the air movement carries the moist air 
away as fast as produced. 

Experiments have actually been made in piping steam 
from large boilers and allowing it to escape through small 
holes in pipes distributed in the orchards. This proved 
an entire failure, as too large a proportion of the heat was 
lost through the smokestacks of the boilers. 




Fig. 76. — Big Six. 



Overhead irrigation has been tried both from horizontal 
pipes and from sprinklers at the top of tall masts. This 
resulted in the formation of large masses of ice on the trees, 
and had to be discontinued. There was also much trouble 
from the freezing and bursting of the distributing pipes. 

Ordinary irrigation has been found to raise the tem- 
perature from two to four degrees above that of adjacent 
nonirrigated areas. For light frosts this is of consider- 
able value, but is open to the following objection. Most 



248 



Citrus Fruits 



citrus growers receive irrigation water in rotation every 
30 days, consequently but few growers would have water 
available at the critical time. Those who pump their 

water do not as a 
rule have pumps 
of sufficient ca- 
pacity to cover 
their entire acre- 
age at one time. 

Certain grow- 
ers at Riverside 
once made an ex- 
periment of heat- 
ing the irrigation 
water by passing 
it through a boiler. 
This was finally 
abandoned as too 
much heat was 
wasted through 
the smokestack. 

6. By mixing 
the air by creating 
artificial wind. — 
This has been ac- 
complished in California in two ways. By drawing 
a wagon about through the orchard bearing a huge 
rotary fan driven by a gas engine ; and by building 
large bonfires at certain points which create a slight 
draught. Both methods have been abandoned as inade- 
quate in the event of a sharp frost. 




Fig. 77. — Eichoff Coal Burner. 



Frost and Orchard Heating 249 

7. By causing frozen plants to thaw out slowly. — If all 
frosted fruit could be picked before it had thawed out and 
placed in storage where it could thaw gradually, a large 
proportion might be saved. Unfortunately, there is no 




Fig. 78. — Hamilton Down Draught. 

time to pick it, and there are no houses big enough to 
hold it. Some growers build fires of wet straw and 
manure on the windward side of the orchards and attempt 
to keep a blanket of smoke over the orchard all of the 



250 



Citrus Fruits 



morning succeeding the frost for the purpose of keeping 
the trees shaded and allowing them to thaw slowly. 
In some cases this has apparently been quite suc- 
cessful. 

8. By the direct addition of heat to the plants and the air 
surrounding them. — ■ This has been accomplished by burn- 
ing wood fires in the orchards, by burning coal in wire 
baskets, by burning smudge fuel 
(shavings and tar), by suspending 
electric heaters in each tree, and 
by burning crude oil or low-grade 
distillate in some form of sheet 
iron receptacle. . Coal is too scarce 
and expensive at ten dollars a 
ton when compared with oil at 
two cents a gallon. Smudge fuel 
is unsatisfactory on account of 
the smoke and the scarcity of 
the material. Electric heaters 
are clean and efficient but too 
expensive to install. There is not 
sufficient electric current available 
to heat more than an extremely 
small proportion of the orchards. 
Several experiments were carried on with small electric 
heaters hung in the trees of the National Orange Com- 
pany's Ranch in southern California during the winter of 
1912-13. About one horse power of electric energy was 
used per tree during the cold period. A thermometer, the 
bulb of which was embedded in an orange on the exterior 
of a heated tree, showed a temperature 7° F. higher 




Fig. 79. — Bolton. 



Frost and Orchard Heating 



251 




Fig. 80. — Coe. 



than a similarly placed instrument on an unheated tree. 
The fruit on the inside of an unheated tree would prob- 
ably have shown a much higher temperature. In a letter 
from H. B. Chase, who conducted the experiments, it is 
stated that the tem- 
perature of the air in 
the orchard showed no 
appreciable increase, 
but the trees and fruit 
came through in much 
better shape than the 
trees which were not 

heated. The only conclusion to be drawn from this 
is that all of the heat given off by the electric heater 
is radiant heat which passes through the air without 
heating it and is absorbed by the limbs, foliage, and fruit. 
The great advantage of such a heater over the oil or coal 

heater at once becomes 
evident. With the 
electric heater the heat 
given off practically all 
gets to the place where 
it is needed, while with 
the other forms of heat 
generators which are 
placed in the rows be- 
tween the trees, the 
heat given off (largely 
convectional heat) is carried up above the trees to a 
great extent and therefore lost. 

Electric heating on a large scale is apparently out of 




Fig. 81. — Pomona Pipe-Line Heater. 



252 Citrus Fruits 

the question because of the lack of sufficient current to 
serve the orchards as a whole. It would seem a pity, 
however, if a few conveniently located orchards might 
not be able to take advantage of idle dynamos during 
early morning hours when street cars and factories are 
not running. 

With the development of enormous quantities of very 
cheap oil in California, the oil burning orchard heater has 
proved itself eminently practicable and is now almost 
universally used throughout the citrus districts. 

ORCHARD HEATING WITH OIL 

In the early nineties, when the oil production of southern 
California was rapidly increasing, Charles Froude intro- 
duced the first oil heater. This heater was later im- 
proved by J. P. Bolton of Fresno, California, formerly 
U. S. Weather Bureau Observer at that place. The frosts 
of December, 1895, in southern California brought about 
a greatly increased interest in frost prevention devices. 
In this month the Riverside Horticultural Club in co- 
operation with the U. S. Weather Bureau, made a num- 
ber of tests of smudging devices, heaters, and vaporizers, 
and published the results of the experiments. It was 
decided then that coal burned in wire baskets, as described 
by Edward Copley, 1 was the most satisfactory method. 
Since this time, however, on account of the tremendous 
development of oil wells in and near the citrus districts, 
oil as a fuel has become cheaper and more popular from 
year to year. 

1 Riverside Press and Horticulturist, April, 1896. 



Frost and Orchard Heating 253 

Requirements of Orchard Heaters 

The ideal oil heater should provide good combustion 
and be as nearly smoke free as possible. It should be 
substantial yet simple in construction and of ample 
capacity. The rate of combustion should be easily 
controlled and it is an advantage to have the parts 
nest well for storage. The covers must effectually 
prevent rainwater from entering. Ease of handling, 
filling, lighting, extinguishing, and efficiency of radiation 
are all important. The cost should be low, usually 
not above '$1 each. 

The combustion should be good, not only to obtain 
as many heat units as possible from a given quantity 
of oil, but to lessen the amount of soot given off. The 
old idea of smudging was to give off as much smoke 
or smudge as possible in order to reduce loss of heat 
by radiation from the earth. While this may have been 
satisfactory to deciduous fruit growers when used at 
blossoming time, it is a positive detriment to bearing 
citrus orchards. The soot collects on the mature fruit 
and necessitates rather expensive special washing. While 
smoke in an orchard does conserve some heat, citrus 
growers would be glad to furnish a little more fuel to 
make up the loss by radiation if they could dispense 
with the soot-laden smoke. Most manufacturers ad- 
vertise smokeless heaters, but few of them as yet ap- 
proach smokelessness, and at the present time none of 
the cheaper oil burners are entirely satisfactory in this 
regard, although marked progress has been made toward 
this end. 



254 



Citrus Fruits 



Good combustion is also important when low grade oils 
carrying a large amount of asphaltum are used. Many 
heaters will not burn out clean with such oil. A cake of 

gummy material is left 
in the bottom of the 
heater which is very 
difficult to remove, 
and soon the capacity 
of the heater is much 
reduced. 

Heaters should be 
as simple as possible, 
for all classes of labor- 
ers will be required to 
operate them in the 
cold, dark nights. 
The less joints, valves, 
and attachments a 
heater has the better. 
Ample capacity is 
important. One gal- 
lon heaters have been 
largely discarded in 
favor of the three and 
five gallon sizes. The 
capacity should be suf- 
ficient for a heater to burn at least eight hours without 
refilling. If small heaters are used, a large number will 
be required, and this increases the labor of handling and 
operating. 

It is important that heaters be fitted with some device 




Fig. 82.— Dunn. 



Frost and Orchard Heating 



255 



for controlling the rate of combustion. This not only 
permits conservation of fuel, but adds a great element 
of safety inasmuch as 
the oil saved in the 
early part of the night 
may be sorely needed 
at some critical time 
in the early morning. 

Some heaters when 
burning low are apt 
to accumulate gas and 
explode, throwing oil 
over the trees and in- 
juring them and less- 
ening the safety of 
the operators. 

The heating equip- 
ment of citrus orchards 
remains in position all 
winter, which is the 
rainy season in Cali- 
fornia. If not well 
protected from rain, 
water will find its way 
into the oil and sink 
to the bottom. When 
the oil is lighted this 
water turns to steam 
and causes the heaters 
to boil over. This results in a temporary bonfire which 
soon burns out and leaves the trees unprotected. 




Fig. 83. — Cane 



256 



Citrus Fruits 



The greater the proportion of radiated, and the 

less convectional heat given off by any heater the 

greater its efficiency. This important principle is often 

BJOT I r M overlooked while con- 

sidenng points appar- 
ently more practical. 
The Indians of Peru 
are said to have used 
for centuries, in pro- 
tecting their crops 
from "gravity" spring 
frosts, a heavy clay 
pot in which char- 
coal is burned. By 
this means they se- 
cured radiated heat 
almost exclusively. 

From a considera- 
tion of the above re- 
quirements it will be 
seen that the develop- 
ment of a thoroughly 
practical and efficient 
oil heater is not an 
easy matter. Four or 
five of the require- 
ments may be combined without much difficulty, but 
some are more or less conflicting. It is especially diffi- 
cult to combine perfect combustion and control of 
combustion with simplicity and cheapness. 




Fig. 84. — Rayo. 



Frost and Orchard Heating 



257 



Types of Oil Heaters 

During the years 1911 to 1914 there was a tremendous 
amount of experimentation in developing types of heaters 
to meet the require- 
ments of citrus growers. 
Almost every one, from 
the local blacksmith to 
the Standard Oil Com- 
pany, seemed to have 
a new idea and was 
sure that he could pro- 
duce the attachment or 
device which would put 
him ahead of everybody 
else. As a result, a very 
large number of different 
heaters were turned out 
and the patent attorneys 
had their hands full. 
Still the improvement 
in heaters goes merrily 
on. We cannot under- 
take a detailed descrip- 
tion of all these different 
heaters, as lack of space 
forbids, and no doubt 
they will all be changed 
more or less during the 
next few years. The ac- 
companying sketches 




Fig. 85.— Hislop. 



258 



Citrus Fruits 




Fig. 



Hamilton Reservoir. 



grouped into three general classes 
heaters ; (b) automatic reser- 
voir heaters ; (c) pipe-line 
heaters. Simple reservoir heat- 
ers are the kind ordinarily used 
which burn from a free surface 
and are adapted to low-grade 
oil. Automatic reservoir heat- 
ers have a patent burner sepa- 
rate and several feet distant 
from the tank. The high- 
grade oil used is fed by a 
small iron pipe which passes 
through the almost smokeless 
flame, the oil being volatilized 
as it is fed. The burner is 
inclosed in a sheet iron pipe 
or drum, which acts as a radi- 
ator. This type has great pos- 
sibilities, but is rather expen- 
sive and cumbersome. 

Pipe-line heaters are fed through 
set above the orchard. There are 



and pictures of heat- 
ers installed in or- 
chards will suffice to 
give a general idea of 
the leading types at 
this time. 

At present these 
heaters may be 
: (a) simple reservoir 




Fig. 87. — Troutman. 

pipes from a large tank 
several forms, some of 



Frost and Orchard Heating 



259 



which burn the oil by dropping it slowly into a super- 
heated cast iron bowl. Others require the orchard to be 
piped with compressed air as well as oil, and the oil is 
finely atomized in the burner and driven with some force 
into the drum, where it burns. The great objection to 
these forms is the expense of piping the orchard, yet there 
is much in their favor. The rate of combustion of all 
the heaters in the orchard may be controlled by operating 
one valve at the tank, and much of the annual expense of 
handling and loss from deterioration of reservoir heaters 
is eliminated. 



Installation of Heaters 

The number of heaters required to 
the acre varies of course with the size 
and variety of trees and the degree 
of cold to be encountered. A fairly 
common equipment consists of one 
three gallon heater to a tree, which 
is usually about ninety to the acre. 
These should be reenforced by an 
extra row around the windward side 
of the orchard. With such an equip- 
ment it should be possible to raise 
the temperature from seven to ten 
degrees for from seven to ten hours, 
depending on wind and other factors. 
Some growers use double this number 
and light only every alternate heater 
during the early part of the night, 




Fig. 



88. — Adamson 
Torch. 



260 Citrus Fruits 

holding the others as a reserve to be lighted only in case 
of emergency. 

It has been found much better to have many small 
fires than a few large ones, as large fires tend to create 
convectional currents which carry much of the heat far 
above the tops of the trees. There is also danger of in- 
juring the trees with large fires. As stated above, one 
heater per tree has been found to be the best plan. 

The heaters are placed on the ground midway between 
the trees and in line with the trees in one direction. If 
placed in the center of the square made by four trees, 
they will be in the way of the wagons which haul the fruit 
out and the oil and manure into the orchards. 

Properties of Fuel Oils 

Petroleum when first taken from the wells is rich in 
gases and lighter substances such as benzine, gasoline, and 
kerosene. Besides these, it also contains such basic sub- 
stances as asphaltum and paraffine. The crude oils* of 
the Eastern states have chiefly a paraffine base, while 
nearly all Pacific Coast oils have an asphaltum base. 
The fuel oils on the market are residuals, the gasoline and 
other lighter oils for which there is a large demand having 
been removed in the refining process. What is known as 
crude oil is not petroleum as it comes from the wells, but 
a refinery residuum containing some of the heavy oils, a 
variable amount of asphaltum, together with some sul- 
fur and a little water. 

The types of oil commonly used are the so-called crude 
oil, smudge oil, slop distillate, and stove distillate. A 



Frost and Orchard Heating 



261 



particular grade of oil is usually recommended for each 
type of heater. A good grade of oil fairly free from 
asphaltum, such as 26 gravity slop distillate for instance, 
costs about two cents per gallon in carload lots delivered 
on siding in southern California citrus districts. The 
cars vary in capacity from 6000 gallons minimum to 12,000 




Fig. 89. — Coal burning orchard heate 

trees. 



Fuel stored in boxes under 



gallons maximum. One great advantage in this oil as a 
fuel is its availability in very large quantities. During 
the blizzard of January, 1913, trainloads were ordered by 
telephone one day, and the oil was dispatched in trains 
having right-of-way, and was delivered, and in some 
instances was actually gotten into the heaters and fired 
before daylight next morning. 

The densitv of the fuel oils varies from 14 degrees 



262 



Citrus Fruits 



Baume to 35 degrees or more. Specific gravity varies 
from .850 or less to as heavy as .975. The heating value 
is usually stated in British Thermal Units, and varies 
from 17,500 to 19,100 B. T. U. a pound. 




Fig. 90. — Orchard heaters ready for lighting. 

Lighter oils are preferred when they are to be pumped 
or delivered through pipe-lines for the reason that in 
cold weather heavy oils become thick and sluggish like 
molasses and are very difficult to handle in small pipes. 



Storage for Oil 

As freezing temperatures often occur several nights in 
succession, it is highly desirable to have an adequate 
means of storing the oil on the ranch near the trees. Stor- 
age capacity should be provided for at least five fillings 
of all the heaters on the ranch. 



Frost and Orchard Heating 



263 



Cement cisterns have been used to some extent for oil 
storage, but are often unsatisfactory. At present, gal- 
vanized circular iron tanks, similar to those used by the 
oil companies, are chiefly used. 

Oil storage tanks should be located if possible on a side 








_ 



Fig. 91. — Orchard heaters in old Valencia grove. 

hill in order that they may be filled by gravity from 
above, and the oil delivered by gravity to the distributing 
wagons below. 

On a number of the larger ranches it has been found 
expedient to install small tanks in various parts of the 
orchards and connect them with the large elevated tanks 
by a system of pipe-lines. The Arlington Heights Fruit 



264 Citrus Fruits 

Company at Riverside has a main steel storage tank of 
500,000 gallons capacity connected with a 6-inch pipe-line 
five and one-half miles long, which serves ten smaller tanks 
each of 12,000 gallons capacity. At intervals through the 
orchard there are "gooseneck" stand pipes from which 
the wagons may be filled. The Limoneira orchard at 
Santa Paula is equipped with two steel tanks holding 
210,000 gallons each and two cement cisterns holding 
100,000 gallons each. This 500-acre orchard has five 
miles of 3- and 4-inch pipe-line and four miles of telephone 
line with a dozen or more telephones located in various 
parts of the orchard. Thirty-five tank w T agons and 
trucks are used to distribute the oil to the heaters. 

Oil Heating Operations 

For delivery of oil to the heaters, tank wagons of four 
or five hundred gallons capacity should be used. Heavier 
wagons are difficult to handle in cultivated or freshly 
irrigated soil. The tank is provided at the rear with a 
large valve or molasses gate, and men following the wagon 
fill the heaters by means of five-gallon buckets or ordi- 
nary oil cans with the tops cut off and provided with 
handles. Filling heaters by means of a trailing hose was 
tried, but has now been abandoned. One group of men 
go ahead of the tank wagon and remove the covers from 
the heaters, and others follow and replace the covers. 

Many kinds of lighting devices have been tried, but 
the Adamson lighter shown in Fig. 78 has come into 
almost universal use. This is merely an oil can in the 
spout of which a roll of wire gauze and asbestos wicking 



Frost and Orchard Heating 



265 



has been loosely fitted. After lighting the wick and in- 
verting the can over an open heater a few drops of gasoline 
or high-grade stove distillate will pass through the flame 
and fall burning into the heater. By use of this device 
heaters may be lighted almost instantly. It is a peculiar 
fact that new heaters are very difficult to light the first 
time. This difficulty is easily obviated by crowding a 




Fig. 92. — Placement of orchard heaters. Extra fuel under trees. 



loose wad of tow or excelsior into the mouth of the down- 
draught tube or by hanging a small asbestos wick on the 
side. This precaution will usually not be necessary after 
a little soot has accumulated in the heater. 

It is the custom to begin firing lemons when the tem- 
perature at three feet from the ground reaches 30° F. 
A safe plan is to watch the young leaves on the lower 
part of the trees and begin firing as soon as they show 
transparent spots indicating that they are freezing. 



266 



Citrus Fruits 



Oranges may be allowed to go several degrees lower 
because they do not carry blossoms and tender young 
fruit in winter as the lemon does. It has been found 

that it is much easier 
to hold the tempera- 
ture at 32° than it is 
to raise it to 32° again 
once it has fallen lower. 
Many growers make 
a practice of lighting 
only every alternate 
pot at first, holding the 
others in reserve to be 
lighted later if needed. 
In case heavy firing 
and refilling becomes 
necessary it sometimes 
is confusing for the 
workmen to tell at a 
glance which heaters 
were lighted first. 
This difficulty may be 
obviated by painting 
a ring with white paint 
on every alternate pot 
in the rows. It also 
saves about one-third 
of the labor of lighting alternate pots to work diagonally 
through the orchard when the trees are planted in squares. 
It often happens that the temperature will not go below 
32 degrees before four or five o'clock in the morning, and 




Fig. 93. — The perforated stack gives 
good combustion but may admit rain- 
water. 



Frost and Orchard Heating 267 

it will be necessary to fire only a few hours. This usually 
pays well, however, for the blossoms and young fruit 
which are on the trees during winter mature in late 
summer when the prices are highest. As soon as the 
sun rises or the wind begins to blow the temperature 
rises and the heaters may be extinguished and the oil 
conserved for future needs. 

Heaters may be extinguished by replacing the covers. 
Occasionally on very cold nights it may be necessary to 
refill the heater during firing operations. This is accom- 
plished by placing the cover on for a few moments until 
the fire is out and then refilling and relighting. 

During the winter 1912-13 one orchardist fired his 
lemon orchard on twenty-nine nights and saved enough 
fruit to pay for his heating equipment and all the expense 
of firing. 

Care of Heaters 

The depreciation of orchard heaters is heavy, especially 
with the cheaper forms. Being exposed to winter rains, 
they rust badly unless well cared for. It is usual to 
charge off from 15 to 25 per cent depreciation for each 
year of service. In the spring when danger of frost is 
past the heaters are emptied into the tank wagons, the 
oil being returned to the storage tanks. Each heater is 
then dipped in asphaltum paint made by melting asphal- 
tum and diluting it with one gallon of stove distillate to 
ten pounds of asphaltum. Some growers even repaint 
the heaters in the orchard after a siege of firing has burned 
the paint off. It is extremely wasteful to store the 
heaters over summer in a rusty condition. In storing the 



268 Citrus Fruits 

heaters it will be found that those whose parts nest well 
are much more economical of space. At present some 
growers store the oil-filled pots under the trees in order 
to save expense of handling. This is satisfactory pro- 
vided they are well painted. One trouble has been that 
careless laborers while hoeing under the trees are apt to 
strike the pots with hoes and cut small holes through 
which the oil leaks, soaking the soil and killing the trees. 

Cost of Oil Heating 

While the cost of heating varies widely and is in some 
cases high, there is no doubt in the minds of those who 
have the most experience that orchard heating pays well, 
especially for lemons. 

Two typical actual expense accounts are given below, 
one for a small grove and one for a large ranch. In both 
cases the figures are for 1912-13. 

Richardson Brothers' Lemon Orchard, Dtjarte, Cali- 
fornia. 1 Fourteen Acres — -1000 Trees 

Equipment 

500 Hamilton heaters, 3 gal $200.00 

700 Bolton heaters, 2 gal 154.00 

Tank wagon, 463 gal. capacity 48.00 

Cement cistern, 8500 gal. capacity 125.00 

Oil buckets 3, lighters 2 6.25 

Four thermometers and automatic alarm .... 40.00 

Total for equipment $573.25 

Oil and labor 

Oil for 16 nights, 16,195 gallons $437.26 

Labor bill for same 201.50 

Total expense for operation $638.76 

1 California Cultivator, Feb. 27, 1913, p. 260. 



Frost and Orchard Heating 269 



Limoneira Orchard Company, Santa Paula, California. 
Five Hundred Acres 1 

50,000 oil heaters (including a thousand of last year's 

pots) $50,000.00 

2 steel storage tanks, capacity 210,000 gallons each 4,885.89 

2 cement reservoirs, capacity 100,000 gallons each 3,000.00 

5 miles of 3-inch and 4-inch pipe-line .... 6,375.03 
35 tank wagons and trucks 4,315.00 

150 spout pails for filling pots 300.00 

200 torches . . ' 200.00 

50 thermometers 150.00 

4 miles of telephone system 750.00 

350,000 gallons of oil in orchard at 2\ cents . . . 8,750.00 

500,000 gallons of oil in storage at 2| cents . . . 12,500.00 

Total $91,225.92 

Reduced to the basis of one acre, the investment is : 

100 heaters $100.00 

Storage space for 1,240 gallons of oil 15.77 

Pipe-line 12.75 

One tank wagon to 14 acres — per acre .... 8.63 

Pails — one to 3^ acres — per acre .60 

Torches — one to 2\ acres — per acre .40 

Thermometers — one to 10 acres — per acre . . .30 

Telephone 1.50 

Oil in heaters — 700 gallons at 2\ cents .... 17.50 

Oil in storage — 100 gallons at 2\ cents .... 25.00 

Total $182.45 

Interest, deterioration, and maintenance : 

6 per cent interest on total investment — $10.94 
15 per cent deterioration on $100 worth of heaters 15.00 

6 per cent deterioration on other equipment . . 2.40 

Estimated handling, painting, and filling (no firing) 5.00 

Total $33.34 

This outlay would seem at first glance to make the 
expense of growing lemons under such conditions pro- 

1 The Monthly Bulletin, California State Com. Hort., Vol. 3, 
No. 1, January, 1914. 



270 Citrus Fruits 

hibitive, and yet J. D. Culbertson, the assistant manager 
of the ranch, states that all of this expense was met by 
the sale of the lemons saved and "fair interest in dividends 
was paid to stockholders out of this year's earnings!" 

SEPARATION OF FROSTED FRUITS 

The Board of Food and Drug Inspection of the U. S. 
Department of Agriculture made the following ruling in 
regard to frosted citrus fruits on January 24, 1913 : 

" Citrus fruit is injured in flavor by freezing and soon 
becomes dry and unfit for food. The damage is evidenced 
at first by a more or less bitter flavor, followed by a marked 
decrease in sugar, and especially in acid content. Fruit 
which has been materially damaged by freezing is inferior 
and decomposed within the meaning of the Food and 
Drugs Act. 

" For the guidance of those engaged in shipping citrus 
fruit, it is announced that, pending further investigation, 
the following principles will be observed in enforcing the 
Food and Drugs Act : 

"Citrus fruit will be deemed adulterated within the 
meaning of the Food and Drugs Act if the contents of 
any package found in interstate commerce contain fifteen 
per cent or more of citrus fruit which, on a transverse 
section . through the center, shows a marked drying in 
twenty per cent or more of the exposed pulp." 

There is much variation in the degree of frozen fruit 
on the same tree. The oranges on the tops of tall trees 
are usually less frozen than those near the ground. Fruit 
on the inside of the tree is less frozen than that on the out- 



Frost and Orchard Heating 



271 



side. Thus when the fruit is picked after a damaging 
freeze the good and bad fruit will be mixed together. If 




Fig. 94. — One type of water separator for frosted oranges. 

the grower does not want to sell all his fruit at a great 
discount as frozen fruit, or run the risk of having trouble 



272 Citrus Fruits 

with Food and Drugs inspectors, he must separate the 
frozen from the uninjured fruit. 

This is not as simple a matter as would at first appear 
for the reason that the fruit usually presents no outward 
indication of its interior condition. 

Usually, after a few weeks, frozen fruit loses a con- 
siderable proportion of its moisture and grows lighter in 
weight. Upon this fact are based all methods of separat- 
ing frozen from sound fruit. Normal oranges have a 
specific gravity of .82, but a few weeks after being frozen 
they dry out and become lighter. If oranges are dropped 
in a liquid the specific gravity of which is slightly lower 
than that of good fruit, the sound fruit will sink while 
the frozen fruit will float. 

The first separations made on this principle were ac- 
complished by using a mixture of kerosene and distillate 
oils. This proved very objectionable on account of the 
odor left on the fruit. D. C. LefTerts of Redlands in- 
vented a machine consisting of a large trough in which 
denatured alcohol of the proper specific gravity is placed 
to a depth of about thirty inches. The fruit is carried 
by conveyors and floated in the alcohol. A double con- 
veyor sweeps the surface of the liquid and delivers the 
frozen fruit to one belt, while the returning conveyor drags 
on the bottom • and delivers the sound fruit at another 
point. More or less difficulty was encountered by the 
alcohol increasing in specific gravity by the water absorbed 
and- the inability of redistilling it on account of national 
laws governing distillation. 

After the LefTerts machines had been used in many 
packing-houses for two years, Frank Chase of Riverside 



Frost and Orchard Heating 273 

invented the water separator, which quickly displaced all 
other methods of separating oranges. This machine con- 
sists of an oblong tank through which water may be made 
to circulate at definite speeds by a small propeller. The 
oranges roll down an incline and drop into the moving 
water from a height of a foot or more. The light frosted 
oranges bob up to the surface quickly, while the sound, 
heavy fruit is slower to rise. Meanwhile the oranges 
have been carried along by the current, the sound fruit 
passing under, and being caught by a horizontal wire 
screen, while the light fruit is carried along above it. At 
the farther end of the tank the two grades are lifted by 
conveyors and delivered to separate bins. By adjusting 
the position of the screen and the rate of flow of the 
water any degree of separation desired may be secured. 
This device enables the grower to save whatever sound 
fruit may have been left, and he may ship it under his 
regular brands with some assurance. The frosted fruit, 
if not seriously injured, may be shipped under a special 
frost brand or it may be used as a fertilizer, or made into 
various by-products. 

The water separator does not work satisfactorily with 
lemons for the reason that they are not round, and the 
depth to which they sink in the water will depend, to an 
extent, on the position in which they happen to strike 
the surface. For the separation of lemons the denatured 
alcohol bath is still used. A layer of lemons is placed in a 
large wire tray and submerged in the alcohol, which has a 
specific gravity of .82. The frosted lemons float and are 
removed by hand. Frequent tests with the hydrometer are 
necessary in order to keep the liquid at the proper density. 



274 Citrus Fruits 

The question is often raised as to whether fruit which 
is only slightly frozen may not improve and fill up with 
juice again if left on the trees. The writer has observed 
this to take place to a limited extent both with lemons 
and Valencia oranges. It appears that the individual 
juice vesicles in any particular fruit vary in their resist- 
ance to freezing. Some reabsorb the water which has 
been drawn out of the cells in order to crystallize, while 
others fail to do so and collapse. A juice vesicle once 
collapsed apparently will not fill up with juice again, 
although the cells making up the walls may retain life. 
Those juice vesicles which do regain their turgidity, how- 
ever, will grow larger than they otherwise would and to 
an extent will fill up the spaces left by the collapsed cells. 
When more than one-half the number of vesicles are de- 
stroyed, the gain in size of the others will hardly be suffi- 
cient to make the fruit marketable. See Fig. 72. 

COOPERATION IN FROST FIGHTING 

The large citrus ranches are in a measure sufficient unto 
themselves when frost fighting is undertaken. On account 
of their size and the large number of men employed they 
are able to organize their forces effectively. The interests 
of small growers, however, who own three, five, or ten 
acres each will be best served through cooperation wherever 
their holdings lie close together. For some years a very 
successful organization of this kind has operated at 
Pomona. It is known as the Pomona Valley Orchard 
Protection Association and is composed of many small 
growers of the district who own in the aggregate about 



Frost and Orchard Heating 



275 



3000 acres. Supplies are bought by wholesale, and the 
labor of firing is carried on by a specially organized force 
which is directed by one manager by telephone from a 
central station. 

Thermometer stations are located at convenient points 
along the roads running through the orchards, and scouts 
mounted on motor- 
cycles make the 
rounds of these sta- 
tions on nights when 
danger from frost is 
imminent. The tem- 
peratures are reported 
to the manager at the 
central office ; and 
when the tempera- 
tures fall dangerously 
low in any section, the 
owners of the orchards 
in that district are 
notified by telephone 
to prepare for lighting 
their heaters. As 
these temperature rec- 
ords are all charted and preserved, they constitute a 
fund of information in regard to air currents and cold 
spots which is of very great practical value in all 
future operations. The example set by this organiza- 
tion should be followed in other districts where many 
small orchards lie near together. 

In concluding this chapter we may say that whatever 




Fig. 95. — Thermometer station of Pomona 
Valley Orchard Protection Association. 



276 Citrus Fruits 

may have been the final verdict in regard to deciduous 
orchard heating in intermountain states, the heating of 
citrus orchards in California has proved a decided success, 
and new heaters are being installed as fast as the factories 
can turn them out. It is safe to say that citrus and 
especially lemon orchard heating in California has come 
to stay — at least as long as cheap fuel oil is available. 
Judging from the present increase in oil production in the 
state there would appear to be no warrant for any un- 
easiness in regard to the fuel supply for many years to 
come. 



CHAPTER XV 
PICKING AND PACKING ORANGES 

California oranges are harvested throughout the year. 
Navel oranges are picked from November 1 to May 1. 
Occasionally Navel picking continues till June. Most 
seedlings and miscellaneous varieties such as Mediter- 
ranean Sweet, Paper Rind St. Michael, Ruby and Malta 
Blood, and Crafton are picked during May and early June. 
Valencias are harvested from June 1 to November 1 or 
later, thus overlapping the next Navel crop. 

Oranges are picked with a great deal of care for the 
reason that carelessness will result in bruises and abrasions 
of the skin which admit the germs of decay. An orange 
with a perfectly sound skin is proof against decay and will 
normally live and respire (breathe) for several months, 
gradually losing water and carbon dioxide until it finally 
dries up, turns brown, and becomes as hard as a wooden 
ball. Oranges will not rot unless they become infected 
with microscopic plants which grow in the tissue, softening 
and breaking it down. All such premature decays (and 
there are many kinds) are preventable. 

As before stated, the unbroken, healthy skin of the 
orange is proof against almost all such decays ; but when 
the skin is abraded in any way, these germs are almost 
sure to get in, as the air is full of them, and most ordinary 

277 



278 Citrus Fruits 

objects, such as gloves, bags, boxes, and the like, are 
always coated with them. The reader should remember 
that these germs or spores are practically ever present, 
and he has only to blow his breath across a moldy orange 
or lemon and observe the billions of minute "seeds" or 
spores floating in a cloud, to realize the enormous number 
produced. If some of this "mold dust" be examined 
under a microscope, each particle will be found to be a 
well-developed spore capable of reproducing the same 
decay whenever it may fall in a suitable place to grow. 

Sometimes in dry weather a very slight scratch, which 
breaks the oil cells only, is cauterized over and healed 
without infection taking place, but this is not always the 
case and it rarely happens in damp weather. 

When the fruit is hanging on the tree the rind is filled 
with water and the surface cells are turgid. They are 
very easily broken when in this condition, while after the 
fruit has been stored in the packing-house a few days 
and the rind dried out somewhat the fruit will endure a 
great deal more in the way of rough handling. This is 
the reason why it is wise to let the fruit cure on the 
packing-house floor for a few days before running it 
through the various machines. 

The following are a few of the ways that abrasions may 
occur, and each of these should be carefully watched : 

a. Clipper-cutting ; careless pickers often allow the 
points of the clippers to extend beyond the stem and cut 
into or prick the skin. 

b. Stem punctures ; all stems must be cut off short 
and smooth, else they will be sure to puncture the skins 
of other oranges during handling. 



Picking and Packing Oranges 



279 



c. Fingernail scratches ; all pickers should be required 
to wear soft cotton gloves which are made especially for 
the purpose and sold for from 60 to 85 cents a dozen 
pairs. 

d. Gravel scratches ; sometimes a careless workman 
will throw an empty box from the distributing wagon in 
such a way that sand or gravel will be flirted into it. 
Before rilling a field box it should always be inverted and 
the bottom tapped to dislodge any grain of sand present. 

e. Nails in boxes ; in many cases nails have been found 
protruding on the inside of field boxes, and their points 
rusted by pricking into perfectly good oranges. 

/. Thorn scratched and dropt fruit ; often with thorny 
varieties considerable care is needed to extricate interior 
fruit from the brush without scratching it. No fruit 
which is dropped should be picked up, as it is almost sure 
to decav. 




Fig. 96. — Tuttle fruit clippers with rounded points. 



The clippers now used are a great improvement over 
the old styles. They have rounded points, and in certain 
types, cup-shaped blades. Most fruit should be double 
clipped, that is, the fruit is separated from the branch 



280 



Citrus Fruits 



with one motion, and then held in a more convenient 
position while the stem is carefully cut off short and 
smooth. The green calyx or " button" should always be 
left on the fruit, for if it is pulled off, an opening is made 
for the entrance of decay germs. 

Only cloth picking bags are 
used, of which there are five 
or more types. They are car- 
ried by a broad strap which 
passes over the shoulder, and 
the most approved types are 
adjustable in capacity and open 
at the bottom, allowing the 
fruit to be emptied into the 
lug-boxes gently and without 
bruising. 

Many different types of lad- 
ders are used, the prevailing one 
having a third leg on hinges 
which is let down through the 
branches and rests on the 
ground near the base of the 
tree. Simple ladders which rest 
against the branches are not 
recommended, as they cause too 
much injury to the fine fruiting brush. Sometimes it 
is necessary to climb up into the crotches of the trees 
to reach inside fruit. This should be avoided as much as 
possible, as the heavy shoes of the pickers scar the bark 
and may carry the germs of gum-disease, especially when 
the surface of the soil is wet. 




Fig. 97. — Dashboard pick 
ing bag. 



Picking and Packing Oranges 



281 



Some growers designate one man in each picking gang 
to do what climbing is necessary and require that man to 
wear a grain sack tied about each shoe in order to avoid 
bruising the bark of the trees. In moving ladders about 
great care should be taken to avoid injury to the fine 
fruiting brush which must be depended upon to bear 
succeeding crops. 

The fruit after being picked is 
transferred to the lug-boxes which 
are never rilled quite full. These 
lug-boxes are then stacked one on 
top of the other on the shady side 
of the trees to await the spring wagon 
which conveys them to the packing- 
house. 

It is often customary to pick the 
fruit from the lower branches first, 
leaving the high fruit till later in 
the season. There are two reasons 
for this. One is that frost is often 
more severe near the ground, and 
low-hanging fruit picked early is out 
of the way of frosts. Secondly, the 
brown rot fungus grows in the soil, 
and during wet spells comes to the surface and fruits. The 
spores are splashed by the rains up on the low-hanging 
fruit, causing decay. It should be pointed out that this 
fungus is different in its action from most other fungi in not 
needing an abrasion for entrance into a sound fruit. The 
spores are motile, and when there is a film of rainwater 
on the surface of the fruit these spores are capable of 




Fig. 98. — Covina 
picking bag. 



282 



Citrus Fruits 



swimming into the stomates or natural breathing pores 
and causing decay. This fungus causes most trouble near 
the coast, and low-hanging fruit need not be picked early 
in the interior valleys on this account. 

Occasionally oranges are picked according to size on 
orders from the packing-house which desires a preponder- 
ance of large or small sizes as the case may be to meet 
the requirements of some certain market. 
Sometimes, also, in the case of a very 
heavy crop, it is advisable to thin the 
fruit on the trees rather than to pick it 
clean the first time. This is done to ease 
the strain on the branches and permit the 
props to be removed. 

It has been customary to pay pickers by 
the day rather than by the box. Piece 
work encourages careless handling and an 
increase in the amount of decay. 

The process known as "sweating," by 
which the color of oranges is changed from 
green to yellow, is illegitimate when em- 
ployed for the purpose of deceiving the 
consumer as to the quality of the orange. Immature fruit 
may not be colored in the sweat-room and sold before it 
is fit to eat. There are cases, however, in which sweating 
is perfectly legitimate. Mature Valencia oranges often 
develop a green color during their second summer on the 
trees, and a light sweating to restore the former yellow 
color deceives no one, and is commonly practiced. In 
some locations also the fruit becomes sweet before it is 
fully yellow. The coloring of such fruit may be finished 




Fig. 99.— Wood- 
ward picking 
bag. 



Picking and Packing Oranges 



283 



in the sweat-room, providing always that such treatment 
is restricted to fruit which is otherwise mature and in 
good condition to eat. 
.Very good prices are usually received for the earliest 




Fig. 100. 



The Wiss clipper now being superseded by the Tuttle shown 
in Fig. 96. 



Navel oranges sent to Eastern markets. This has resulted 
in recent years in considerable competition for the early 
markets and the shipment of much fruit which is im- 
mature and not satisfactory. Sometimes oranges are 
picked as early as the first week in October, while still 
perfectly green in color, colored by 
sweating and hurried to market. 
While some of this fruit brings high 
prices the result is disastrous for the 
much better fruit which follows. This 
unwise shipment of immature fruit re- 
sulted in so much loss and dissatisfac- 
tion among the growers of both Cali- 
fornia and Florida that the legislature 
of the state of Florida on June 13, 
1913, passed an immature fruit law which has since 
been enforced with some good results. This law forbids 
the shipment of green fruit between September 1 and 
November 5 of each vear which shows bv test to 




■vAj 



Fig. 101. — Metal at- 
tachment for prop- 
ping limbs. 



284 



Citrus Fruits 



contain in the juice more than 1.3 per cent of acid. 
A simple and cheap method of making the acid test 
was worked out by the state chemist and placed at 
the disposal of all growers. Between September 1 and 
November 5 inspectors traveled through the state taking 
samples and making tests at the various packing-houses. 




Fig. 102. — Worm brushes used for polishing oranges. 

The simple field test was used, but in the case of dispute 
the remainder of the sample was sent to the state chem- 
ist for more accurate analysis. 

Some time before the Florida law was passed the Federal 
Board of Food and Drugs Inspection took notice of the 
artificial coloring of immature oranges by sweating, and 
made the following ruling : 



Picking and Packing Oranges 



285 



FOOD INSPECTION DECISION 133 



The Coloring of Green Citrus Fruits 

The attention of the Board of Food and Drug Inspection 
has been directed to the shipment in interstate commerce 
of green, immature citrus fruit, particularly oranges, which 
have been artificially colored by holding in a warm, moist 
atmosphere for a short period of time after removal from the 
tree. Evidence is 
adduced showing 
that such oranges 
do not change in 
sugar or acid con- 
tent after removal 
from the tree. 
Evidence further 
shows that the 
same oranges re- 
maining on the 
tree increase 
markedly in sugar 
content and de- 
crease in acid content. Further, there is evidence to show 
that the consumption of such immature oranges, especially 
by children, is apt to be attended by serious disturbances of 
the digestive system. 

Under the Food and Drugs Act of June 30, 1906, an article 
of food is adulterated "if it be mixed, colored, powdered, 
coated, or stained in a manner whereby damage or inferi- 
ority is concealed." It is the opinion of the Board that 
oranges treated as mentioned above are colored in a manner 
whereby inferiority is concealed and are, therefore, adulter- 
ated. 




Fig. 103. — Rope feed hopper. 



286 



Citrus Fruits 



The Board recognizes the fact that certain varieties of 
oranges attain maturity as to size, sweetness, and acidity 
before the color changes from green to yellow, and this 
decision is not intended to interfere with the marketing of 
such oranges. 

H. W. Wiley, 
F. L. Dunlap, 
Geo. P. McCabe, 
Board of Food and Drug Inspection. 
Approved : 

James Wilson, 

Secretary of Agriculture, 
Washington, D. C . , March 28, 1 9 1 1 . 




Fig. 104. — Orange sizing machine. 



The enforcement of this ruling has done a certain 
amount of good, but it has not entirely put a stop to the 
irresponsible shipment of worthless fruit, for the reason 



Picking and Packing Oranges 



287 



that it applies only to fruit which has been artificially 
colored. 1 




Fig. 105. — Box press and nailing machine. 

1 Where there is living vegetable tissue there is respiration, 
and carbon dioxide and water are given off. That the respiration 
of stored oranges takes place at the expense of sugar and acid 
and results in the gradual reduction in the amounts of these 
substances has been shown to be true by investigations carried 
on in the U. S. D. A. Bureau of Chemistry in 1905. 

"During the storage (of Navel oranges) there was a slight loss 
in acid and in sugar. This is confirmatory of similar results 



Citrus Fruits 



Navel oranges color earlier and become sweet earlier 
in central than in southern or northern California. The 
apparent advantage in sweetness of 
early oranges from southern San 
Joaquin Valley is not due so much 
to an early increase in total sugars as 
it is to an early increase in the ratio 
between sugar and acid. Colby 1 has 
shown that it is the early decrease 
in acid, together with the early color- 
ing, which enables the growers in the 
San Joaquin Valley to market their 
oranges early. 

Recently C. L. Alsberg, chief of 
the Bureau of Chemistry, U. S. D. 
A., suggested that as a result of in- 
vestigations carried on, the northern 
district oranges may be considered to be immature when the 
juice does not contain soluble solids equal to or in excess of 
eight parts to each part of acid present, acid to be calcu- 




Fig. 106.— Citrus fruit 
truck. 



with apples and peaches, and is probably due to the decomposi- 
tion of acid and sugar in the respiration of the fruit. " . . . "The 
loss of acid and sugar noted above is to be explained, as in the 
case of apples, by the consumption of these substances as a 
result of respiration of the fruit." — W. D. Bigelow and H. C. 
Gore, "Ripening of Oranges." Read before A. A. A. S. in 
New Orleans, 1905. Contribution from the Bureau of Chemistry, 
U. S. Dept. Agr. — Published in Journal American Chemical 
Society, Vol. 29, No. 5, 1907. 

1 G. E. Colby, "Comparative Examination of Shipping Navel 
Oranges from Northern, Middle, and Southern California," 
California Agr. Exp. Sta. Rpt, 1898-1901, Part II, pp. 243- 
251. 



Picking and Packing Oranges 



289 



lated as citric without water of crystallization. It was 
decided to base this figure upon the acid solids ratio in 
preference to the acid sugar ratio for the reason that the 
growers and packing-house foremen would be able to 
make the necessary analyses, which would be impossible 
in the case of sugars. 

Since this valuable suggestion was made growers and 
shippers throughout the early districts have applied the 
test quite generally and are 
cooperating in limiting ship- 
ments to fruit which shows 
the 8-1 ratio. The effect of 
this has been very beneficial 
as shown by market reports. 

Shippers of oranges will do 
well not to pick the fruit 
until it is in condition to be 
enjoyed on the tables of the 
growers themselves. If the 
orange industry in northern FlG - 107 - ~ Packin § stand - 
California is to grow to great proportions, it must do so 
on a basis of satisfactory fruit. Every orange sent to 
market should stimulate in the buyer a desire for more 
of the same kind. 

The sweat-room. — The sweat-room is an air-tight, fire- 
proof chamber usually built separate from the main part 
of the packing-house. Beneath a false floor are placed 
kerosene burning stoves of a type which does not give 
complete combustion. The hot gases and water vapor 
pass up through the floor and envelop the fruit. The 
temperature is controlled by ventilators in the roof and is 




290 



Citrus Fruits 



kept for oranges at 100° F. for from three to five days, or 
until the oranges are properly colored. During this time 
the air in the sweat-room should be kept quite moist to 
prevent wilting and shriveling of the fruit. This will 
require close watching, as the air will dry out with some 
lots of fruit and tend to remain saturated 
with other lots. Pans of water may be 
set on the stoves, and occasionally it is 
necessary tp wet down the fruit and 
the sides and floor of the room in addi- 
tion. The fruit should be graded ac- 
cording to shade of color, the lightest 
being placed next the door, so that it 
may be removed earlier than the rest if 
desirable. The air should be a little 
less than saturated with moisture. 

When the coloring of citrus fruit is 
forced too rapidly the buttons (stems) 
shrink away and drop off. This is very 
undesirable, as fruit without buttons is 
not supposed to keep as well and is dis- 
counted in the markets. When used to 
excess the same gases which color the 
fruit throw the buttons. 
In very few places in California does the fruit come to 
the packing-house sufficiently clean to pack. In interior 
valleys it is covered with a layer of dust, and near the 
coast it is apt to show scale insects or the black smut 
(Meliola camellia?) which is a fungous growth on the honey 
dew or excretions of scale insects. If fruit is simply dusty, 
it is run through a series of rapidly revolving dry roller 



Fig. 108. 
squeeze. 
size. 



Picking and Packing Oranges 



291 



brushes. In some cases it may have a spray of water 
directed upon it while in the brushes or it may pass in 
water between two series of submerged brushes. In the 
latter case a tank is necessary, and it is good policy to 
disinfect the wash water against brown rot infection. 
Wash water for oranges is usually disinfected by the 



\ 




Fig. 109. — Car squeeze. Large size. 

addition of one pound of permanganate of potash to 1000 
gallons of water in the morning, and at noon \ pound is 
added to the same water. The water in the tank is 
changed each day. 

After being washed the fruit is conveyed by belts to 
drying racks in the open or under cover, or is run through 
an air-blast dryer. 

The fruit next passes on belts or roller ways before the 



292 Citrus Fruits 

graders who, considering color, shape, smoothness, and 
blemishes, sort the salable fruit into three grades, stand- 
ard, choice, and fancy, placing each grade on a separate 
belt which conveys it to its respective automatic weighing 
machine where the proper proportion of each grade is 
credited to the grower. After the oranges pass the weigh- 
ing machines their identity is merged in the general pool 
of the house. 

The fruit next passes through the sizing machines, of 
which there are a great many different types, and each 
size is delivered to a separate bin. The bins are carefully 
padded on bottom and sides with- cotton cloth, and 
have movable sides which provide for adjustment of 
capacity. 

Box shooks are usually bought in Oregon or northern 
California, and the boxes are made in the basement of 
the packing-house. They are made either by hand or 
by an automatic box making machine. A standard box 
of California oranges is 12 by 12 by 26' inches outside 
measurement. It is divided in the middle by a partition. 
For purposes of computing freight charges it is estimated 
to weigh when packed 72 pounds. 

On the end of each box is pasted a paper label, usually 
a five-color lithograph, showing some picture appropriate 
to the brand. Each packing-house or association has a 
series of brands copyrighted for its own use. In addition 
to this the finest quality fruit sold through the Cali- 
fornia Fruit Growers' Exchange bears the additional 
"Sunkist" label of the Exchange. The variety and size 
of the fruit and the packer's number is stenciled on the 
end of each box. Boxes which are liable to be sold in 



Picking and Packing Oranges 293 

New York State are now stenciled with the exact dimen- 
sions and cubical contents of the box. 

Box shooks are made of Pacific Coast pine exclusively. 
The standard 8 slat orange <box requires 5iVo feet of 
lumber and costs about 132 cents delivered. The standard 
lemon box contains \ foot more lumber and costs on an 
average 15| cents. The cheaper grades of tissue wrap- 
pers come from mills in Oregon and California, while the 
fine grades come from Hamburg, N. J. The paper is 
printed in Los Angeles from wide rolls on cylinder presses. 
The cost printed and delivered to the packing-houses for 
the 10X10, an average size, is about $17.50 a hundred 
thousand. A pound contains about 414 sheets. Box 
labels are procured from lithograph, houses and are usually 
done in five colors. They cost about $3.00 per thousand. 
Special cement coated nails are used which cost in large 
lots about three cents a pound. Metal box strapping 
comes from New Jersey chiefly in 6500 foot reels and costs 
about $1.46 a thousand feet. From 18 to 24 inches of 
strapping is used on each box. Most of the larger packing- 
houses use beveling machines for the ends and partitions 
and box making machines for putting the boxes together. 

Both women and men are employed as packers, women 
being most largely used. The empty box is placed on a 
packing stand which rests on rollers and has a revolving 
top. The hod holding tissue wrapping paper is placed 
over one end of the box. The packers stand beside the 
sizing bins, and wrapping each fruit in printed absorbent 
tissue paper, place it in the box with great dexterity and 
skill, averaging about sixty boxes a day. The fruit is 
placed in the box in its respective order of arrangement 



294 



Citrus Fruits 




Picking and Packing Oranges 295 

according to the size. Each size of fruit has its own order 
of arrangement and the size is designated in the house 
and on the market not by the diameter of each, orange, 
but by the number required to fill a box. 1 

Oranges 

Size Average Diameter in Inches 

64 3f 

80 3^ 

96 3f 

112 3^ 

126 3| 

150 3 

176 21 

200 .. . 2| 

■216 2f 

250 2\ 

288 2f 

324 2\ 

360 ....... . 2| 

A very high pack is customary, and after the covers are 
forced on and nailed the boxes are usually delivered by 
automatic carrier to the car or precooling room. One 
hundred field boxes will usually pack out about sixty 
packed boxes. The cars vary in capacity, depending on 
whether they are provided with collapsible ice bunkers. 
The standard car of oranges contains 384 boxes loaded 
two tiers on end and six rows wide and including sizes 
96, 112, and 250, and not over 20 per cent of the 126 
size. The remainder of the car may be divided among 
the 150, 176, and 216 sizes. Cars other than standard are 
discounted from 25 to 50 cents a box on the market 
according to the number of off sizes they contain. 

1 For further rules governing packing, see Chapter VIII. 



296 Citrus Fruits 

The boxes are set with two inch air spaces running 
lengthways the car. Each tier of boxes is braced in 
position by a narrow strip running across the car and 







BE - ' Ji 

- 


■.■;:■:■,■> 


- r .i ":- < 








■gj^,^' 1| 








mt: 




- 

J 



Fig. 111. — Orange packers at work. 

nailed to each box. As the tiers are set the slack through- 
out the car is taken up by a device known as a " car 
squeeze." A copy of the manifest card showing the num- 



Picking and Packing Oranges 297 

ber of different sizes and their location in the car is tacked 
on the inside wall near the door. 

The freight is figured on an estimated weight of 72 lb. 
to the box, and is $1.15 a hundred pounds to points on 
the Missouri River and eastward. Icing charges are 
extra. 

Precooling 

The term " precooling " properly applied relates to the 
reduction in the temperature of any given lot of fruit before 
it is dispatched on its journey to market, in contradistinc- 
tion to the usual metnod of reducing the temperature 
gradually in transit. It has been found by experiment 
that when warm fruit is loaded into cars with ice and 
started on its journey across the desert that before the 
fruit in the center of the boxes is thoroughly chilled, 
decay has set in. This decay is checked, but on unloading 
the fruit in the warm, humid climate of the East such 
decay spreads rapidly. With precooled fruit the decay 
has not been allowed to become so much advanced, and 
cars do not require such frequent re-icing. Precooling will 
not take the place of careful handling. 

Inasmuch as citrus fruits, when carefully handled, keep 
excellently for long periods at ordinary temperatures, 
precooling is not as valuable with them as it is with other 
more tender and quickly perishable fruits. Several 
packing associations have adopted the practice of sending 
their fruit to market " under ventilation " or without ice, 
but it requires great care in picking, handling, and packing 
to be able to do this successfully. 

The large precooling plants which chill a whole train 



298 Citrus Fruits 

load of thirty cars simultaneously by driving or circulating 
a blast of cold air through the cars, are owned by the rail- 
road companies who desire that precooling be considered 
a function of the transportation companies. Some 
packing associations which had built small precooling 
plants of their own objected to the above point of view and 
fought their case in the courts for several years, finally 
winning their point before the U. S. Supreme Court in 
January, 1914. The Court ruled that $7.50, for each re- 
icing, the rate set by the Interstate Commerce Commission, 
was reasonable and applicable to precooled shipments. 
The rate previously charged by the railroads for icing cars 
was $62.50 for the trip, regardless of whether much or little 
ice was needed. Inasmuch as precooled cars only require a 
comparatively small amount of ice en route, the saving to 
the growers by this decision amounts to about $30 a car. 

About 55 per cent of the oranges shipped East go forward 
under ice. In very cold weather and especially for cars 
sent to the extreme North, it is advisable, before loading, 
to paper the inside of the car with several thicknesses of 
heavy building paper to prevent the fruit from being 
frozen en route. 

The average haul for cars shipped east of the Mississippi 
River is 2585 miles and the average time between San 
Bernardino, where the Santa Fe overland citrus trains 
are made up, or Colton, where the Southern Pacific trains 
are made up, and New York is about fourteen days. 

After many years of effort the citrus growers have gained 
from the railroads the right of diversion, which means 
that a car of oranges may be billed to Chicago, for in- 
stance, and when it arrives should the Chicago market 



Picking and Packing Oranges 



299 



be unfavorable it may be diverted to Cleveland or Buffalo 
or Boston or to any other place toward the East and 
within that traffic zone without additional charge. 

There are two concerns in southern California which 




PmeCone 

BRAND 

H WASHINGTON NAVELS 



6R0WN "=PACKtD BY 



Highland 

Orange 

association, 

^Highland, 
5an bernardino co.^^s^ 
Galiforn 




Fig. 112. — A typical orange box label. 

make a specialty of designing and constructing packing- 
houses and manufacturing special equipment. Most 
orange houses consist of a basement, where shook and 
other supplies are stored and where boxes are made, and 
a packing floor where fruit is handled from delivery wagon 



300 



Citrus Fruits 



VUU' .UUU'A^U'.U^^UUUV^U'^UWr 



V«. k UUV\^ ' 










Picking and Packing Oranges 301 

to the car. The fire hazard is high and losses are rather 
frequent. Most of the houses belong to a local mutual 
insurance association which prorates and assures the 
■losses as they occur. 

There are at present about 200 packing-houses in active 
operation in California, besides a large number of sheds 
and old houses which operate only at infrequent intervals. 
The capacity of the houses varies from one to twenty cars 
a day. 

The associations which are affiliated with the Exchange 
enjoy the privilege of buying ranch and packing-house 
supplies through the Fruit Growers' Supply Co. This 
is a non-profit cooperative organization through which 
the growers pool their orders at low cost. The Sup- 
ply Company has an authorized capital of one million 
dollars and in 1914 did a business of $3,319,062.04 at an 
operating expense to the members of f of one cent on 
each dollar of business transacted. 



CHAPTER XVI 



PICKING AND PACKING LEMONS 



The picking and packing of lemons differs radically 
from that of oranges as described in the previous chapter. 

Lemons are usu- 
ally picked from 
ten to twelve 
times a year, the 
heaviest pickings 
coming in March 
and April and 
the lightest in 
August and Sep- 
tember. It is a 
peculiar and un- 
fortunate fact 
that the heavy 
pickings come at 
a time of year 
when there is lit- 
tle demand for 
lemons and the 
lightest pickings 
come during the 
picnic and 
Fig. 114. — Picking lemons. lemonade season, 

302 




Picking and Packing Lemons 



303 



when the demand is greatest. For this reason the proper 
storage of spring lemons becomes one of the important 
functions of the lemon packing-house. 

The following typical example of an actual yield of a 9 f- 
acre mature lemon orchard of mixed Eurekas and Lisbons 
growing near Covina, Los Angeles County, gives a good 
comparison of the various pickings : 



Record of Lemon Pickings. Season 1910-11 
Orchard of Mr. N. D. Mussey 



Pool 


Date 


Lug-boxes 


Pounds 


1 


Sept. 19 


76 


3,698 


2 


Oct. 19 


60 


2,880 


3 


Nov. 17 


289 


13,852 


4 


Jan. 3 


520 


24,470 


5 


Feb. 1 


832 


39,415 


6 


Mar. 18 


1,122 


50,906 


7 


May 3 


1,120 


51,350 


8 


May 30 


196 


9,268 


9 


July 21 


298 


14,224 


10 


Aug. 30 


52 


2,506 


Total 


4,565 


212,569 



The method of picking lemons from the trees is much the 
same as with oranges except that the use of the ring and 
consequent searching about in the foliage among fruit of 
all sizes makes picking slower and more expensive. Es- 
pecial care should be used to prevent dead twigs and other 
trash from falling into the picking sacks as the weight of 



304 



Citrus Fruits 



the lemons against such objects in handling will cause 
scratches in the skin. In some sections special picking 
sacks with closed tops are used to prevent this. In this 
type of sack the fruit is introduced at the side near the 
top. 

For hauling to the packing-house the growers generally 
use a factory-made wooden wagon with steel skeins 




Fig. 115. — Two-story lemon packing house, Glendora, California. 



on which they place a wide flat rack usually about 8 feet 
wide and 14 feet long. The racks are made locally and 
are set on the gears over bolster springs. It is not un- 
common to see a string of three or more of these wagons 
hooked together and being drawn by the gas tractor 
which is used for cultivating the orchards. 

Lemons differ from oranges also in being valued for 
their acid rather than for their sugar content. A green 



Picking and Packing Lemons 305 

lemon therefore is better than a yellow " tree ripe " one 
provided it is fully sized and mature. For these reasons 
lemons are picked altogether according to size rather than 
color. The pickers carry wire rings which are slipped over 
each lemon, and every fruit which fails to pass through the 
ring is picked. In summer a ring 2\ inches in diameter, 
inside measurement, is used ; while in winter and spring 
a ring one-sixteenth of an inch larger is used, inasmuch 
as the fruit will be held longer and will undergo greater 
shrinkage. 

On account of the demands of the markets mentioned 
above, there is a tendency to pick often in summer, care- 
fully searching for every lemon which may be up to size. 
This fruit is quickly colored in the sweat-room and hurried 
to market while prices are high. 

SWEATING AUTUMN LEMONS 

The sweating of lemons is for the purpose of quickly 
changing the green color to a whitish yellow. While 
the practice of sweating oranges is sometimes abused, 
lemon sweating is always legitimate as it in no way de- 
ceives the buyer. In fact the mature but green lemon 
properly colored in the sweat-room and hurried to market 
is usually sourer, and therefore better, than the lemon 
which has been kept in storage for several months and 
has consumed a small portion of the acid in the process 
of respiration. 

For best results, lemons should be fired intermittently. 
The air of the sweat-room should be kept saturated with 
moisture, and beads of water should be in evidence on 



306 Citrus Fruits 

the ceiling at all times. If the air is allowed to become 
dry, the lemons will quickly shrivel. The temperature 
should be kept at 90° F. or ten degrees lower than for 
oranges. So far it has been impossible to fully color 
green lemons in five days and retain the buttons, as the 
same quality of the gas mixture which changes the color 
causes the buttons to drop off. Inasmuch as sweated lem- 
ons are sold and consumed quickly, the loss of the buttons 
is not as serious a matter as would otherwise be the case. 



STORAGE OF WINTER LEMONS 

In the late winter and spring when it becomes advisable 
to hold the fruit for summer markets, the problem of the 
lemon packer is very different from that of early fall. 
Instead of sweating the fruit and thus accelerating the life 
processes as much as possible, he now wishes to retard 
to the greatest possible degree these same life processes. 
The fruit is therefore picked with very great care in order 
to prevent abrasions. On arriving at the packing-house 
the lemons are carefully washed in a brush washer. For 
disinfection against brown rot, one pound of bluestone is 
added to each 1000 gallons of wash water in the morning 
and one-half pound added to the same water at noon, the 
water being changed each morning. To prevent the 
bluestone from corroding metal tanks it is well to apply 
a thick coat of asphaltum paint to the inside of the tank. 

The lemons are now separated into three grades accord- 
ing to color alone, known as green, silver, and tree-ripe ; 
the silver being those fruits which are just beginning to 
lose the deep green color. Each of these grades is placed 



Picking and Packing Lemons 



307 



loosely in packing boxes and stacked up, a car in each 
stack, on the storage floor. Lemons are often kept in this 
way six or even 
eight months, 
but the fruit 
picked after April 
1 is much shorter 
lived than that 
picked earlier. 
Lemons picked 
green will keep 
much longer than 
those allowed to 
turn yellow on 
the tree. These 
tree-ripes are 
kept separate and 
shipped first. 
Lemons will also 
keep much better 
near the coast 
than in the in- 
terior valleys, 
where much more 
expensive storage 
houses must be 
provided in order 
to control the 
humidity. The 

great problem is to give plenty of ventilation in damp 
weather in order to prevent decay and to reduce the 




Fig. 116. 



Lemon washing machine and sort- 
ing table. 



308 Citrus Fruits 

ventilation, or withhold it entirely in warm dry weather 
to prevent the fruit from losing moisture and shrivel- 
ing. The relative humidity of the air in the storage 
house should be held as near 80 per cent as possible, but 
this is very difficult to accomplish in interior valleys, 
where the humidity of the air varies from 90 per cent to as 
low as 10 per cent. In order to control the temperature 
and humidity each carload stack of lemons is inclosed in 
a heavy duck tent. These tents are usually made of 8 oz. 
special army duck, and are 10' wide, 10' high, and 20' long. 
This size includes one carload of lemons. This tent is 
open at the bottom, and is open at the four corners, which 
are laced so that any part of the fruit may have ventila- 
tion, without interfering with fruit that it is not necessary 
to ventilate. These tents are also built in other sizes, 
which is sometimes necessary to fit the space in a packing- 
house, but this is the size that is most generally used. 
The tent is hung from the ceiling on a frame, there being 
eyelets in the top to fasten to frame. In some of the 
packing-houses in interior districts the tents have been 
abandoned and the fruit is stored in large basements, 
usually built of concrete, with outside shutters which 
provide for ventilation. 

Unless the lemons have been very carefully handled 
from the orchard to the packing-house, a great deal of 
decay is almost sure to develop in storage. Lemons are 
always handled more carefully than oranges and the brush 
washer is about the only piece of machinery they are 
allowed to pass through. On account of the absence of 
machinery, a lemon packing house presents a very different 
aspect from an orange packing house. 



Picking and Packing Lemons 



309 



When the fruit is taken from storage it is graded by 
hand into fancy, choice, and standard, each grade being 
placed one layer deep in broad flat trays. Stacks of these 
trays of fruit are weighed and the proportion of the differ- 
ent grades credited to the grower of the fruit. All through 
washing, storing, and grading each grower's fruit is accom- 
panied by a ticket attached to the guide box. When each 




Fig. 117. — Lemon curing tents in packing-house near the coast. 



of several hundred growers has four or five pickings in 
greens, silvers, and tree-ripes, all in storage at one time, 
the task of keeping account of each lot of fruit necessitates 
a well-organized system. In the packing-house lemon 
varieties are not kept separate, and the name of the variety 
is not stenciled on the end of the box as is customary with 
oranges. 

Lemon packers use the same packing stand that is 



310 



Citrus Fruits 



used for oranges, but instead of packing from bins contain- 
ing fruit all of one size, they pack from the trays, sizing the 
fruit by eye and hand, the range of sizes in each grade 
running from 210 to 540 per box. Lemons sizing 300 to 
360 to the box are in greatest demand on the markets, 
Southern markets preferring the smaller and Northern the 
larger sizes. In one or two of the newer lemon packing 
houses, sizing machines built especially for lemons have 




Fig. 118. — Truck for handling stacks of lemon trays. 



been installed. These are operated very slowly in order 
to avoid injury to the fruit. Most packers still regard 
sizing machines for lemons with suspicion. 

The standard lemon box has an outside measurement of 
11 by 14| by 27 inches and is divided in the center by a 
partition. For the computation of freight charges a 
box of lemons is estimated to weigh 84 pounds. The 
standard car of lemons contains 312 boxes. 



Picking and Packing Lemons 311 




p IG jig. — Packing lemons from sorting trays. 



312 Citrus Fruits 



Lemons 

Size Average Diam- 

eter in Inches 

210 2| 

240 2| 

270 1\ 

300 2| 

360 2| 

420 2f 

490 2 

540 11 

Lemons were formerly shipped under ventilation from 
November to March, and under ice the remainder of the 
year. Some shippers who have learned to handle their 
fruit with extreme care have abandoned ice altogether to 
their great profit. In 1912-13 only 14 per cent of the 
lemons shipped were iced. The average haul to market is 
2283 miles, being 304 miles less than the average haul 
for oranges. This difference is accounted for by the fact 
that a larger proportion of California lemons are marketed 
west of the Missouri River, thus avoiding, to a certain 
extent, the sharp competition with Italian lemons through- 
out the Atlantic seaboard. 

The freight rate on lemons from California to New York, 
Chicago, and intermediate points has been fixed at SI. 00 
per hundredweight after a long and expensive contest in 
the courts, the lemon growers finally winning their con- 
tention. 

PICKING POMELOS AND TANGERINES 

Pomelos are picked from the middle of December to the 
following August and many growers keep some fruit for 
home use on the trees the year round. The total ship- 



Picking and Packing Lemons 313 

ment of pomelos from California is not large, being about 
200 cars per year. Ordinarily the fruit is stored in lug- 
boxes for a few days until the rind becomes soft and 
pliable. After this the fruit is packed in orange boxes 
and handled like oranges. Pomelos improve somewhat 
in flavor with storage and proper curing, and for best 
results, this fruit should be very carefully picked in 
February or March and held in storage precisely as are 
lemons until May, June, and July. 



Pomelos 

Size Average Diam- 

eter in Inches 

64 3| 

80 3| 

96 3| 

126 3| 

150 3 



Large quantities of pomelos are grown in Florida, Cuba, 
Porto Rico, and the Isle of Pines, and these dominate 
the markets of the eastern United States. California 
pomelos are marketed mostly within the state and to 
some extent in the intermountain country and the Pacific 
Northwest. Only a few are sold in New York. On 
account of the state quarantine, Eastern pomelos cannot 
be brought into California for sale. At present a large 
portion of the California pomelos found on the markets 
are poor in quality. This is due to the fact that but little 
attention has been paid to pomelos and most growers 
tend to treat them in every respect like oranges. That 
the climatic and soil conditions in some parts of California 
are well suited for the production of a first-class pomelo 



314 



Citrus Fruits 



is evidenced by the fact that a few skillful growers market 
their fruit in New York at very remunerative prices in 
competition with Eastern fruit. 

Tangerines are the only variety of mandarin orange 
grown to any extent in California. They are picked, 
packed, and shipped in much the same fashion as oranges 
except that, being a fancy fruit and in limited demand, 
they are not shipped in car lots. It is customary to 
market tangerines gradually, including a dozen boxes or 
half-boxes in a car of oranges. 



T^yy-v^ t/ottse. 



o- 







hum— 



<£U J eavS '/y^^^ /^yaw 



£yer<2//&// 



Fig. 120. — -Lemon packing house. Compare with Fig. 113. 



PACKING-HOUSES 



There are hardly two packing-houses in California which 
have the same capacity, arrangement, or equipment. In 
general the orange house is small and is equipped with a 



Picking and Packing Lemons 



315 



great deal of machinery, while the lemon house is large 
and contains but little machinery. The fruit is received 
at one end from wagon scales and moves gradually through 
the house as it is washed, graded, sized, packed, and so on, 
until the packed boxes are loaded on the cars at the oppo- 
site end. Various types of mechanical conveyors are em- 
ployed to save labor in handling the fruit and packed boxes. 




ijw» 



/* 



rt 




V •■-■■'•fv 


, ' Fp, k pj 


:t .y : t 


w' *l 


'< T " 






— __, I * 




Oommstoi Fsyrr Co. 1 




5AHTA 8ARSIU*A,CAiifO«<ift. 



Fig. 121. — Typical lemon box label. 



Cleanliness is very important. Xo decaying fruit 
should be allowed in the house, as the spores given off 
tend to increase the amount of decay. All culls should 
be conveyed by belt from the grading table to some bin 
or outhouse entirely separate from the main packing- 
house and situated to leeward of it. 



316 



Citrus Fruits 



The comfort of employees should be provided for by 
rest rooms and lunch rooms. The main packing floor 
should be well lighted by glass skylights, for it has been 
found that the efficiency, comfort, and spirit of the em- 
ployees are greatly improved by clean, airy, and well 
lighted work-rooms. 




Fig. 122. — -Combination box label. 

Some packing associations confine their work to packing 
and shipping, while others take charge of all picking, 
pruning, and in some cases fumigating of the groves. 
In packing lemons, especially, it is a good plan for the 
packing-house manager to control the picking. The San 
Dimas Lemon Association, for instance, keeps account 
of the fruit picked by each crew of pickers, and as this 



Picking and Packing Lemons 317 

fruit comes out of storage and is sorted over a careful 
account is kept of the percentage of each kind of decay. 
In this way a check is kept on the pickers, and if decay 
due to careless handling occurs it may be traced back and 
the blame placed where it belongs. Each foreman of 
a picking crew knowing that he is responsible for any decay 
which may develop in his lemons takes pains to instruct 
his men in the best methods of handling the fruit. At the 
end of each season a substantial prize is awarded the 
picking crew in whose fruit the least amount of decay 
has developed. 

Pickers are drawn from many nationalities. Americans 
receive about $2 a day, while Japanese and Hindus are 
paid twenty cents an hour. A responsible picking 
foreman of considerable experience in handling lemons and 
men may receive $75 or more a month aside from a 
variable bonus at the end of the season. 



CHAPTER XVII 

BLEMISHES OF THE FRUIT AND THEIR 
PREVENTION 

A large increase in the production of citrus fruits 
will mean, if it means anything, a keener competition 
in the markets. In order to meet this increased competi- 
tion, California growers and packers are being encouraged 
to adopt higher ideals in grading and packing. With 
more rigid grading the cull-heaps near many of the 
packing-houses assume large proportions. A conserva- 
tive estimate places the direct loss from cull oranges 
alone, aside from frozen fruit, in excess of a half-million 
dollars a year. 

It is well worth while, therefore, to make a study of the 
cull-heap, classifying and determining the relative im- 
portance of the various blemishes which cause oranges 
to be thrown into a lower grade or into the cull-heap. We 
will also consider how far it is practicable and by what 
means the proportion of culls to packed fruit may be 
reduced. 

The blemishes of citrus fruits may be classified according 
to their causes. For convenience we may group them 
under four heads, namely : insect, fungus, mechanical, 
and physiological blemishes. 

318 



Blemishes of the Fruit and their Prevention 319 

As a result of counts of Navel culls made in twelve 
packing-houses during January and February, 1910 and 
1911, it appears that on the average, the most prolific 
causes of culls are as follows, according to their impor- 
tance : splits, bruises, thorn stabs, thrips scars, sunburns, 
and worm holes. These six kinds of blemishes are re- 
sponsible for upwards of seventy-five per cent of the 
culls. These counts, however, did not take into consid- 
eration the brown spot which usually does not develop 
until the fruit has left the packing-house. 

INSECT BLEMISHES 

Insect pests and their control will be discussed rather 
fully in Chapter XXII and it is only necessary here to 
name those blemishes of the fruit which are due to insects. 
They are : thrips scars ; tortrix worm holes ; scale insects 
such as red, yellow, purple, and the sooty mold which 
follows and grows upon the excretions of the black, gray, 
and brown scales ; mealy bugs ; red spiders ; silver mites ; 
grasshoppers ; katydids ; and some others. 

The presence of a few scale insects on fruit intended 
for some markets in the East need not condemn it, but 
there are other markets, such as certain ones in British 
Columbia, where inspectors condemn all scaly fruit even 
though citrus fruits be not grown in the region. 

FUNGUS BLEMISHES 

The fungi which produce injury to the fruit are : brown 
rot, Pythiacystis citro'phthora ; blue mold, Penicillium 



320 Citrus Fruits 

italicum; green mold, Penicillium digitatum; gray mold, 
Botrytis cinerea; sooty mold, Meliola camellice; cottony 
mold, Sclerotinia libertiana; gray scurf, fungus not as 
yet identified; wither-tip, Colletotrichum gloeosyorioides ; 
black rot of the Navel, Alternaria citri; and stem-end 
spot, Cladosvorium sp. (secondary). 

Most of the fungus diseases which cause blemishes on 
the fruit result in complete loss. The nature of these 
diseases, together with control measures, will be discussed 
in detail in Chapter XXI. 

The fungus causing gray scurf or scab on lemons has 
not as yet been identified. The fungus apparently acts as 
a secondary agent; the primary cause is probably the 
slight bruising of the young tender fruit by the wind. 
The best remedy for this trouble is the growing of 
windshields and close planting of the lemon trees. By 
proper pruning also the branches may be made stiffer 
and more resistant to the swaying and whipping effect 
of the wind. 

The stem-end spot of oranges is a very different thing 
from stem-end rot, and occurs mostly on Navels and 
on fruit which has hung late on the trees. It consists 
of a breaking down, browning, and shrinking of the skin 
in certain small spots near the stem. Ordinarily this 
causes little injury, but occasionally during rainy weather 
a species of Cladosporium grows on the dead tissue of 
these spots, giving them a black color which detracts 
very much from the appearance of the fruit. The only 
remedy at present available for this trouble is to pick 
the fruit early in those orchards where the trouble becomes 
serious. 



Blemishes of the Fruit and their Prevention 321 



MECHANICAL BLEMISHES 

Much otherwise good fruit is ruined by carelessly in- 
juring the fruit mechanically. Growers and packing-house 
men rarely realize how serious are the losses resulting 
from such causes. 

Bruises. — Fruit which is bruised by careless handling 
is almost sure to decay. Careful handling should be the 
cardinal principle of every picker and packer. When a 
stack of boxes of fruit is accidentally overturned in the 
packing-house, the fruit should be set aside for ten days 
and then sorted over, the decaying fruit being eliminated. 

Thorn stabs. — Much fruit is ruined by thorns. In wet 
weather such thorn-pricked fruit decays, but in dry 
weather the broken skin may cauterize and result in a spot. 
Sometimes a fruit continually swinging against a thorn 
will develop a thick horny rind at that point, which ruins 
its appearance. Thornless varieties, careful pruning, and 
windbreaks are the remedies. 

Cultivator scars. — Cultivators and other tillage im- 
plements should be covered by a smooth tin shield which 
will allow low-hanging fruit to slide over them without 
injury. Metal projections on harness are also objection- 
able. When it is necessary to' cultivate close up under 
the trees a great deal of fruit will be ruined unless pro- 
tected by some sort of shield attached to the implements. 

Clipper cuts. — When the use of pointed clippers was 
in vogue the loss from clipper cuts was very great. Now, 
however, round pointed clippers are used, and there is no 
excuse for clipper-cutting the fruit. 

Stem punctures. — When the stems are not properly 



322 



Citrus Fruits 



cut off square and close, they puncture a great deal of 
fruit in the box, and as they pass through the packing- 
house machinery. A close watch kept on the pickers 
should prevent this. 

Machine injuries. — Some years ago a certain packing- 
house foreman complained of excessive decay which could 
not be explained. Finally one of the employees dis- 
covered a loose screw in one of the guide bars of the 
brushing machine hopper. The sharp head projected an 
eighth of an inch and made a little nick in every orange 
which rolled by. Passing over the brushes each nick 
was thoroughly inoculated with decay germs. The guilty 
screw head was driven home, after which the decay in 
transit dropped from 35 per cent to 4 per cent. The 

remedy for this is to 
keep a close watch 
for screw heads or 
, ' splinters on all ma- 

chinery and for pro- 
< " **$. Vv - , r jecting nails in field 

. (-.' ,*'* «'"* -« boxes. 

JTls^C, Fuv ligation scars. — 

Oftentimes fruit is 
pitted and burned by 
carelessly overdosing 
trees with gas during 
fumigation. Fumiga- 
tors should be held re- 
sponsible for such in- 
jury. Occasionally, however, it happens that a sudden 
change in the weather or condition of the atmosphere 




Fiu. 123. — Fumigation scars. 



Blemishes of the Fruit and their Prevention 323 



will result in wholesale pitting of fruit even with the same 
dosage which was harmless a few hours earlier. No 
remedy has been found for this difficulty, and fumigators 
are not to blame. Fortunately such occurrences are rare. 

Shoulder spots. — Where two oranges grow touching 
each other the point of contact is often shown by a light 
colored area with a reddish spot in the center. Such 
spots are not very serious and cannot be remedied unless 
the fruit be thinned. Thinning citrus fruits has never 
been practiced in California. 

Rail scars. — Hail storms are of rare occurrence in the 
citrus districts. When they do occur they pit the fruit. 
If the hail is followed by dry weather, most of the pits will 
dry and little injury will result. In wet weather, however, 
some fruit will de- 
cay on the tree 
with blue or green 
mold, while in some 
cases a species of 
Cladosporium will 
grow on the pits and 
turn them black in 
color. 

Soil scars. — Where 
heavy crops of fruit 
bend the branches 
down much fruit often 
rests on the ground. 
When the wind moves 
the branches the rubbing of the fruit on the ground 
causes a gray callous spot which ruins its appearance. 




Fig. 124.- 



Scar caused by rubbing on the 
ground. 



324 Citrus Fruits 

Windfalls. — Occasionally strong winds will whip a 
large part of the orange crop from the trees, as was the case 
in September, 1911. It is rarely safe to send a windfall 
to the packing-house, as it is very apt to develop decay. 

Cement dust. — In certain localities the fruit is coated 
on the upper side with a crust of cement dust which comes 
from near-by cement mills. This dust collects in the 
pores of orange skin and sets, being very difficult to 
remove. It injures the appearance and reduces the grade. 

PHYSIOLOGICAL BLEMISHES 

This class of blemishes is not only large and the losses 
serious but the causes are as a rule not well understood. 
The total number of troubles of this kind is very large 
and new ones are continually appearing. Only the most 
important will be mentioned here. 

Sunburn. — Both oranges and lemons which hang fully 
exposed to the sun are often injured. The exposed side 
becomes dwarfed in growth, resulting in malformation, 
and the skin of oranges becomes thick and pale colored 
and adheres tightly to the flesh. In interior valleys where 
the sun is very hot the skin may die and a hard black spot 
result. In such situations the trees should be pruned in 
such a way as to encourage the production of inside fruit, 
which is always much finer in appearance. Lemons are 
often noticed in the markets which are lop-sided, the dis- 
tance from stem to apex being greater on one side than the 
other. This is caused by slight sunburn and is a sure 
sign that the lemon grew in an exposed position on the 
tree. There is a curing house trouble of lemons known as 



Blemishes of the Fruit and their Prevention 325 

red rot, or, more properly, red blotch, which develops as 
a rusty brown color, gradually drying down into a sunken 
condition with a dark red or black color. This has been 
attributed to sunburn, as it is most common in lemons 
from exposed parts of the trees. 

Frost. — The losses from frost are of course very large, 
but many fruits are only slightly frosted, and while they 
should be packed under a frost label they are good for 
consumption. Oranges usually exhibit no outward signs 
of frost unless severely frozen. Occasionally, however, 
certain oranges, especially those having more or less thick 
skins and growing low down on the north side of the tree 
will show a number of characteristic brownish spots on the 
exposed side even though but slightly frosted. 

Off-bloom. — Occasionally orange and pomelo trees will 
blossom out of their regular season. The cause of this 
is not always apparent, although it is often due to irregu- 
larities in irrigation. Fruits developing from off-blooms 
are usually malformed and inferior. Navel off-blooms 
produce fruits with sunken instead of protruding navels. 
Pomelo off-blooms produce fruits which are distinctly 
pear-shaped as compared with the regular crop. Regu- 
larity and thoroughness of irrigation and cultivation will 
reduce the amount of off-bloom fruit to a negligible 
quantity. 

Mottled-leaf. — This disease is not at present well 
understood. It results in the production of very small 
oranges and lemons of a whitish color, often quite unfit 
for packing. (See Chapter XXI.) 

Exanthema. — This trouble appears on the fruit as dark 
reddish blotches or crusts. In severe cases the fruit is 



326 Citrus Fruits 

dwarfed in growth and cracks open on the trees. (See 
Chapter XXI.) 

Malformation. — Many kinds of malformations are 
common. They may be divided into two classes : those 
due to sporting such as corrugations and color stripes of 
the rind, bottled-necked fruits, and others, which may be 
remedied by pruning out all of the sporting branches; 
and those due to an excess of food and teratological factors. 
Many Navel oranges, especially those borne on the top- 
most branches, exhibit a double or proliferated navel. 
Often this takes the form of a small secondary orange 
superimposed upon the navel. These are very common 
and are always thrown into the cull-heap because the 
small orange would have to be broken off before packing 
and this would result in decay. Often twin oranges 
partly attached are met with which are discarded for the 
same reason. The fruit borne near the large upright 
central branches often has coarse, grooved skin about the 
stem. This is caused apparently by the superabundance 
of food and may be largely prevented by proper pruning. 

Broum spot. — The brown spot of the Navel orange may 
be described as occurring irregularly over the surface of 
the orange. From one to fifty or more spots may develop 
on a single fruit. The spots vary in size from a mere 
point to one inch in diameter, averaging about one-fourth 
inch. 

This brown spot occurs only on the Navel oranges, and 
is uniformly worse on fancy, smooth, thin-skinned fruit. 
The total money loss from this particular spot is very 
large. For further particulars see Chapter XXI. 

Cracks and splits. — Cracks differ from splits in being 



Blemishes of the Fruit and their Prevention 327 

transverse rather than longitudinal openings in the rind 
of the orange. They are of rare occurrence and their 
cause is unknown. Splits, on the other hand, are very 
common and cause heavy losses, especially with Navel 
oranges in interior valleys. Splits are of two kinds : 




Fig. 125. — Orange splits. Side splits above and navel -end splits below. 



side splits and navel splits. Side splits are caused 
by teratological cavities or seams in the skin. Thus 
weakened the skin is unable to withstand the growth 
pressure, and a split results. 

A Navel orange which is split even a fourth of an inch at 
the navel must not be packed for long distance shipment, for 
such an opening is almost sure to be inoculated with decay. 



328 



Citrus Fruits 



All such oranges must be graded out but may often be sold 
to local peddlers for enough to pay for picking and hauling. 
The most common theory in regard to the cause of splits 
is that an irregular water supply, causing wide variations 
in the moisture content of the soil, produces a greater 
fluctuation in the growth of the interior than in the skin 
of the orange. Such a theory is quite reasonable, but such 
a cause should be regarded as contributory only, inasmuch 

as only a part of the 
fruit on any given tree 
will split. If a number 
of navel-split oranges are 
cut in longitudinal sec- 
tions, it will be found, 
almost without excep- 
tion, that the thickness 
of the rind varies, being 
quite thick and often 
creased at the stem end, 
and as thin as paper near 
the navel. Specimens 
with uniform thickness 
of skin very rarely split. 
Hot, dry spells of weather 
alternating with damp cloudy weather, together with careless 
irrigation, cause a high percentage of splits among this class 
of oranges. While much may be done toward overcoming 
this loss by careful irrigation and cultivation, the most 
important remedy is probably the propagation of trees 
from carefully selected bud-wood. By this means we 
may largely eliminate from our future orchards the un- 




Fig. 126. — Horizontal cracks are very 
different from splits. 



Blemishes of the Fruit and their Prevention 329 



desirable types which are so prone to split during un- 
favorable weather. 

Puffing. — When oranges are left too long on the trees, 
they will often become puffy. The rind becomes weak, 
with many cross creases and much unevenness. Finally 
the whole orange 
becomes soft and 
structureless. The 
walls of the juice 
vesicles become much 
thickened and the 
juice partly disap- 
pears, leaving the 
fruit dry, crumbly, 
and insipid. The 
remedy for this 
trouble is to pick the 
fruit earlier in those 
localities where puff- 
ing is serious. 

P etec a. — Thi s 
trouble appears in 
the form of deep 
sunken pits in the 
rind of lemons after they have been in the curing house 
for some time. The tissue at these spots is found to 
be dried and shrunken prematurely, somewhat after the 
fashion of the brown spot of the Navel orange. The 
cause of peteca is not known. 

Dry center of lemon. — A peculiar trouble which has be- 
come quite general in recent years. The vesicles collapse 




Fig. 127. — Peteca of lemon. 



330 Citrus Fruits 

in groups, turn brown, and dry up. Injury is always 
greatest near the blossom end and is often accompanied 
by germination of the seeds while still within the fruit. 
In advanced cases the interior of the lemon may become 
filled with a mass of roots from the seeds. While this 
trouble results in a loss of juice, the housewife who cuts 
the lemons through the center is notapt to discover their 
inferiority as there is little surface indication of dry center. 
In many ways this trouble resembles bitterpit of the 
apple. At present neither the cause nor a remedy is 
known. 



CHAPTER XVIII 
BY-PRODUCTS 

Until very recently it has been the custom in California 
to haul the cull fruits from the packing-houses and dump 
them in waste places. A very few growers returned the 
culls to the orchards and plowed them into the soil for 
the sake of their humus value and the small amount of 
plant-food they contain. But the bulk of the culls have 
been thrown away, and when we consider the enormous 
waste resulting from this practice the question arises as to 
whether a part at least of this large tonnage of fruit may 
not be profitably converted into valuable by-products. 

That citrus by-products are in strong demand in the 
United States is proved by our annual importation of 
these items from abroad. The imports of the year 1909 
are fairly typical of other years and are given on page 
332. The values given are the appraised wholesale values 
at the port of export and would be considerably higher 
if appraised in this country. 

At the present time nearly all citrus by-products are 
produced in Europe, while small amounts come from 
Paraguay, China, and California. 

The chief reason why citrus by-products have not been 
more largely produced in the United States is that the 

331 



332 



Citrus Fruits 



cost of labor is from three to five times greater than in the 
citrus producing regions of Europe. At present, however, 
there is a widespread interest in this subject in California. 
Several small factories are already in operation, and several 
more are in process of construction. 

Importation of Citrus By-products into the United 
States for the Year ending June 30, 1909 



Citric acid — lb 

Citrate of lime — lb 

Lemon, lime, and sour orange juice 
Orange and lemon peel not candied, 

preserved, or dried 

Citron or citron peel, candied or dried 

— lb 

Citron preserved in brine — lb. 
Orange and lemon peel, preserved, 

candied, or dried — lb 

Oil of bergamot — lb 

Lemon oil — lb 

Lime oil — lb 

Oil of neroli or orange flower — lb. 
Orange oil — lb 

Total 



Quantity 


Value 


243,010 


$74,209 


3,917,274 


489,031 




81,386 




4,833 


991,341 


79,519 


4,075,835 


100,224 


436,129 


20,692 


89,957 


281,211 


405,695 


358,197 


21,991 


9,973 


23,184 


170,342 


87,591 


151,860 



,821,477 



In Europe the citrus by-product industry is largely 
centered on the Island of Sicily and in Calabria. In 
these districts the two chief products are citric acid and 
lemon oil. About one-third of the total lemon crop of 
this region is consumed in the manufacture of citrate of 
lime, and from the peel of these same lemons comes the 



By-Products 333 

enormous quantity of essential oil, or essence of lemon, 
which furnishes practically the world's supply. 



COMMERCIAL BY-PRODUCTS 

For convenience those by-products at present manu- 
factured on a commercial scale will be grouped separately 
from a number of domestic recipes which are included. 
Several of the products described under domestic recipes 
may of course be produced on a commercial scale, should 
the demand warrant. 

Citric acid. — Citric acid is manufactured from the juice 
of the lemon chiefly, although lime juice is used to some 
extent. The peel is first removed and used for the pro- 
duction of lemon and lime oil which will be described later. 
The lemons are halved and the pulp scooped out with a 
sharp spoon. The pulp is then passed through toothed 
cylinders which shred it, and the juice is extracted from 
the mass by a high power press. The crude juice con- 
tains water in abundance, citric acid, malic acid, several 
kinds of sugar, albuminoids, and mucilage. The crude 
juice is filtered, placed in boilers, and heated nearly to the 
boiling point. Finely powdered chalk, mixed to a cream 
in water, is slowly added, while the hot liquid is being 
constantly stirred. The chalk or carbonate of lime 
unites with the citric acid, forming calcium citrate, which 
is insoluble and precipitates from the juice as a white 
powder, which is collected, washed, and dried into cakes. 
Great care is used to add just enough chalk to take up 
the citric acid as shown by litmus tests. As citric acid 
must pay a duty of seven cents a pound on entering the 



334 Citrus Fruits 

United States and citrate of lime is free, most of the Italian 
product is shipped to this country as citrate of lime, and 
the final step in the process is completed in this country. 
This final step consists in treating the citrate with dilute 
sulphuric acid, which forms sulphate of lime and leaves 
citric acid in solution. This solution is evaporated in 
leaden boilers until the pure citric acid crystallizes out, 
and is washed and dried. Citrate of lime contains about 
65 per cent of citric acid. 

Lemon oil, orange oil, bergamot oil, and lime oil. — The 
peel of all citrus fruits is thickly dotted with small glands 
yielding an essential or highly volatile oil. The oils 
from the different kinds of citrus differ considerably in 
their characteristics. These oils are in great demand 
for flavoring extracts and perfumery, and the demand 
for the different kinds is in the order given. Of these, 
lemon oil is used in much the largest quantities. Any 
person may easily demonstrate the presence of this vola- 
tile oil by squeezing a piece of fresh peel in such a way 
as to cause the oil to spurt out into the flame of a lighted 
match. It will burn with a flash, showing its high vola- 
tility. 

The major part of the oils now on the market come from 
Sicily and Calabria. The contrivances for extracting the 
oil are very crude, much hand labor being necessary. 
As before stated, the fact that labor in Italy costs only 
one-third as much as in California is the chief reason why 
California has not produced a larger amount of citrus oils. 

After the pulp has been removed from the halved lemons 
and pressed for citrate, the peels are soaked in cold water 
for a few hours to increase the turgidity of the cells. They 



By-Products 335 

are then taken by men who press out the oil entirely by 
hand. The pressers sit on low stools with a small lipped 
bowl between their feet. Across the top of the bowl 
rests a strong notched stick which supports a large sponge. 
Each half lemon is placed against the sponge and given 
three or four sharp squeezes, using almost the entire weight 
of the body. The oil spurting out of the peel is caught by 
the sponge and drips through it into the bowl below. 
From time to time the bowl is raised and the oil is blown 
off by the breath into a graduated glass receptacle, the 
lip retaining the small amount of water and residue. 
After the oil is filtered through a paper filter it is ready for 
market. In Calabria a crude machine is used in which is 
a bowl lined with sharp metal points. The fruit is placed 
whole in this bowl and revolved, the points puncturing 
the peel, from which the oil drips through an opening in 
the bottom of the bowl. This device is called an ecuelle, 
and is used chiefly in the making of bergamot oil, for the 
reason that bergamot oranges are round in shape and 
revolve to better advantage in the machine. 

Some few operators lacerate the rinds of lemons or 
oranges and distill the oil, but the use of this method 
results in water white oil of very inferior grade. 

A large amount of oil of limes is made in the West 
Indies. The oil is extracted from whole fruit by hand 
in ecuelle pans, the pulp being later pressed and the juice 
concentrated by evaporation and sold as lime juice to be 
used as a drink. 

Unfermented orange juice. — "A very palatable and 
attractive beverage can be made from oranges. The 
chief difficulty is the mechanical one of rapidly and eco- 



336 Citrus Fruits 

nomically separating the juice from the solid parts of the 
fruit. The juice can easily be made perfectly and per- 
manently clear by settling and filtration. Sulfurous acjd 
in very small amounts (4 ounces potassium metabisulfite 
to 100 gallons of juice, an amount well below the limit 
allowed by law) is necessary to prevent fermentation and 
the production of a bitter taste during settling. The 
cleared juice keeps perfectly after bottling if pasteurized 
at 180° F., which does not injure the flavor perceptibly. 
Good oranges will yield over 130 gallons per ton; frozen 
oranges a much less amount." l 

Orange oil, for which there is a good demand, may be 
extracted from the skins of the oranges used in the manu- 
facture of juice. 

Orange vinegar. — A good quality of vinegar may be 
manufactured from the juice of cull oranges which are 
well matured and have a total sugar content of 10 per 
cent or more. Cruess 2 has shown that orange juice con- 
taining 11 per cent will, on fermentation, give about 5.5 per 
cent of alcohol, and that this on conversion into acetic 
acid will yield about 5.5 per cent of acid, which is consid- 
erably over the legal limit of 4 per cent of acetic acid. 

Inasmuch as many samples of orange juice may be 
expected to contain 9 per cent or less of total sugars, it is 
apparent that the resulting vinegar will closely approach 
or even fall below the legal limit unless considerable care 
be used in the selection of the raw material as well as in 
the fermentation process. 

1 W. V. Cruess, "Utilization of Waste Oranges," Calif. 
Exp. Sta., Bull. No. 244, 1914. 
2 Ibid., p. 164. 



By-Products 337 

Orange wine. — Most of the so-called orange wines found 
on the markets are made from orange juice flavored with 
orange oil, fortified by the addition of alcohol or brandy, 
and sweetened by the addition of sugar or sirup. Such 
liquids, of course, have no right to be called orange wine. 

An agreeable pure orange wine can be made by the use 
of proper methods. Such methods consist in " defecating 
the fresh juice after the addition of moderate amounts of 
potassium metabisulfite to prevent fermentation for a 
short time, fermenting the clear juice with pure yeast, 
and filtering the finished wine to clear it. This cleared 
wine may be turned into sparkling orange wine by the 
addition of a small amount of sugar and by subsequent 
fermentation in bottles." 1 

Candied citron. — Most of the citron consumed in the 
United States comes from the Mediterranean region and 
especially from the Island of Corsica. The chief reason 
why citron is not more largely produced in California is 
the difference in the cost of labor. Citron is admitted to 
the United States from Corsica duty free when it is shipped 
pickled in brine or ordinary sea water. Practically all 
imported citron is candied in this country. There is one 
firm now engaged in the growing and processing of citron 
near Riverside, California. 

The fruit as it first begins to assume a bright yellow color 
is picked and placed in brine for a month or longer, the 
brine being renewed occasionally. Sometimes tender 
young leaves of the citron tree are soaked with the fruit 
to deepen the green color. The fruit is then boiled in 
fresh water to remove the salt and soften it. It is then 

1 Ibid., p. 170. 



338 Citrus Fruits 

halved, the pulp and seed scooped out, and immersed in 
cold fresh water to intensify the greenish color. After 
this it is covered with hot sugar sirup and allowed to 
stand three or four weeks, during which time the strength 
of the sirup is gradually increased. The fruit is then 
put into boilers with crystallized sugar sirup and cooked ; 
then allowed to cool, more sugar is added, and it is cooked 
again until it will take up no more sugar. It is then dried 
and packed in wooden boxes, each piece being coated with 
white sugar crystals and wrapped in tissue paper. 

Oil of neroli. — This product is made chiefly in the vicin- 
ity of Grasse in the French Riviera. Neroli is made by 
distilling the flowers of the bitter or bigarade orange, 
known in California as sour-stock. Both oil and water 
pass through the still ; and as they condense the oil col- 
lects on the surface, is skimmed off, and sells for a very high 
price (from $20 to $50 a pound) . Three hundred pounds 
of flowers are required to make one pound of neroli. The 
water which distills over absorbs some perfume from the 
oil and is sold as eau de fleur d'oranges, bringing about 
twenty-five cents a gallon. 

Petit grain oil. — This oil is used in perfumery and is 
prepared by distilling the young and tender leaves and 
shoots of both bitter and sweet oranges. It sells for from 
two to five dollars a pound. A large part of the petit 
grain oil now comes from Paraguay, where orange trees 
have run wild and occur in forests over a large area. 

Tincture of orange flowers. — This is a perfume which 
is prepared by steeping the fresh flowers in alcohol until 
all the perfume has been absorbed by the alcohol. 

Essence of orange flowers. — This perfume is produced 



By-Products 339 

in large quantities in Europe and imported into this 
country. Apparently there is no reason, except the high 
cost of labor, to account for the lack of production in the 
United States. As orange trees produce many times the 
number of flowers that are needed for setting a crop, and 
most of them fall off normally, the preparation of essence 
need not hinder fruit bearing. The making of the per- 
fume is a simple matter, and the preparation of a small 
supply for home use might furnish a pleasing pastime for 
young people living among orange groves. In the early 
morning orange blossoms are collected as soon as the petals 
begin to fall, by shaking the tree over a sheet spread on the 
ground. A tree yields from two to ten pounds of flowers. 
The perfume is generally extracted by enfleurage. Shal- 
low trays containing layers of fresh blossoms are slipped 
into the grooved sides of a large air tight box. The box 
is filled with trays, but between each two trays is inserted 
a sheet of wire gauze or linen holding a thin layer of wax 
or mixed grease. The odor of the flowers is absorbed by 
the grease, the flowers being replaced by fresh ones every 
morning for a month, when the grease, or " pomade " as it 
is called, is collected and treated with alcohol for a month. 
The odor leaves the grease and passes to the alcohol, 
which is then known as essence of orange flowers. 

Dried and candied peel. — Both orange and lemon peel 
are in good demand, both candied and dried. When dried, 
the peel is simply removed from the pulp, cut into thin 
shreds, and dried in the sun. When candied, the process 
is very similar to that used for citron, and the orange and 
lemon peels are not shredded, but left in halves. 

Lime juice. — Large quantities of limes are grown on the 



340 Citrus Fruits 

islands of the West Indies. The green limes are harvested 
and shipped to market in barrels, turning yellow on the way. 
The ripe fruit which falls to the ground is gathered up and 
converted into several different by-products, such as citric 
acid, lime oil, and lime juice. In making raw lime juice 
which is to be used as a beverage, only clean, sound fruit 
is used. The juice is expressed by passing the fruit be- 
tween heavy granite rollers. The juice is allowed to stand 
until the mucilage or albuminous matter is thrown down, 
after which it is filtered and bottled. If the fruit used 
is clean and sound, the raw juice should keep without 
any preservative being added. Lime juice cordial is made 
by mixing the raw juice with various brandies and other 
ingredients. 

Orange paste. — A large amount of orange paste is used 
by confectioners. It is made by grinding and macerating 
fresh orange peels, and after the addition of an equal 
weight of sugar evaporating down into hard cakes which 
are broken up and packed in wooden buckets. This or- 
ange paste is one of the few citrus by-products which is 
already being manufactured in California. 

Crystallized baby oranges. — • The small green oranges 
which drop from the trees during June and known as the 
"June drop " may be gathered and made into a pleasing 
confection known as crystallized baby oranges. Fruits 
between one-half and one inch in diameter are best and 
should be gathered frequently and not allowed to wilt on 
the ground. The fruits are placed in brine, gradually in- 
creasing the strength until fermentation is prevented. 
They may remain in brine indefinitely, provided the brine 
is changed occasionally. When ready for processing, the 



By-Products 341 

fruits are boiled in several changes of fresh water until 
free from salt, and tender, after which a hot weak sugar 
sirup is poured over them. This solution is replaced by 
one more dense each day until the fruits will take up no 
more sugar. They are then dried and dipped in a very 
thick sugar solution and allowed to cool slowly when the 
sugar will crystallize out over the surface. The fruit is 
now ready for packing. 

Glaced kumquats. — Chinese and Japanese prepare a 
quantity of glaced kumquats, a certain amount of which 
is shipped into this country. The fruits are picked when 
ripe and several slits made in the sides. Sometimes the 
seeds are squeezed out through the slits, sometimes not. 
The fruit is boiled until tender and then carried gradually 
through a series of sugar solutions of increasing density 
until they will take up no more. They are then dried and 
dipped in a very heavy hot sirup and quickly dried. In- 
stead of crystallizing the sugar will glace over the surface. 

DOMESTIC RECIPES 

In addition to the foregoing there are a large number of 
pleasing preserves, marmalades, and other preparations 
which may be made to advantage in the home kitchen. 
Some of these, such as Dundee marmalade, are manu- 
factured in quantity and shipped to distant markets. 
While it is deemed inadvisable to give a very large num- 
ber of home receipts, still a few of the more important 
ones may prove of interest and value. 

Orange or lemon jelly. — Slice fruit thinly, rind and all, 
place in double boiler with cover, and boil slowly for 20 



342 Citrus Fruits 

minutes without stirring. Press out juice and filter 
through several thicknesses of muslin. Add a little more 
than an equal volume of sugar. Boil on slow fire three 
minutes and pour into jelly glasses while hot. In some 
cases a small amount of gelatine is added before boiling, 
but if properly made as above directed this should not be 
necessary. 

Orange marmalade. — Large amounts of orange marma- 
lade are made in Dundee, Scotland, from whence it is 
shipped to all parts of the world. The oranges used in the 
manufacture of this marmalade are the bitter oranges 
grown in the district of Valencia in Spain and shipped to 
Scotland after being shredded and canned. Most of the 
marmalade made in California is made from sweet oranges 
and pomelos. A little of the characteristic flavor of the 
bitter orange may easily be secured by replacing a few of 
the sweet oranges with bitter ones. 

Slice one dozen oranges thin, throwing away ends, and 
one-half dozen lemons, removing all seeds. Measure 
the fruit, and add half as much water. Let stand over 
night. Next morning boil the fruit in the same water 
until tender. Remove from fire and weigh and to each 
pound of fruit and liquid add one pound of sugar. Boil 
until it jellies, which should require about twenty minutes. 
Do not have the fruit too ripe ; it should be fresh and firm. 

Pomelo marmalade. — Slice one pomelo, one orange, and 
one lemon, rejecting seeds and core. Measure the fruit 
and add to it twice the quantity of water. Let stand in 
an earthen dish over night and next day boil slowly until 
peel is tender. Let stand another night and the second 
morning measure and add an equal volume of sugar. 



By-Products 343 

Place in covered double boiler and boil slowly for a half 
hour or until it jellies. The fruit should not be stirred 
during boiling. 

Citrus-rhubarb marmalade. — Take six pounds of fresh 
rhubarb, four large oranges, four lemons, and one large cup 
finely chopped walnuts. Cut the oranges and lemons into 
thin slices, rejecting ends and seeds. Add to the rhubarb, 
which has been cut into small pieces. Put four large cups 
of sugar over this and let stand over night. Next morning 
add four more cups of sugar and boil down. Just before 
placing in jars and while still hot stir in the chopped wal- 
nuts. 



CHAPTER XIX 
MARKETING 

The different methods of selling California citrus fruits 
may be grouped for convenience under four general heads, 
which, with the proportion of fruit now (1913-14) sold by 
each method, are approximately as follows : 

13 % Miscellaneous sales. 
5 % Sales by independent growers who ship to market. 

20% Independent association sales. 

62% Sales through the California Fruit Growers' Ex- 
change. 

Under the head of miscellaneous local sales, fruit is dis- 
posed of in various ways. It n\ay be sold either for a lump 
sum on the trees to itinerant packers and speculators, or it 
may be contracted for by hotel syndicates to be delivered 
as needed. The management of the dining cars and eating 
houses of a large railroad company, for example, often se- 
lects certain crops of oranges which are bought for a stated 
price per pound, to be picked and delivered as needed. 
Commission men will sometimes secure a contract for a 
certain amount of fruit of a certain grade to be delivered 
in the East or in Australia or Hongkong, and then send an 
agent around the country buying the fruit wherever it 
can be secured. Such buyers will usually contract with 

344 



Marketing 345 

some independent local packing-house for the packing of 
the fruit. 

Under the head of independent grower-shippers are in- 
cluded certain large growers who have sufficient acreage 
to warrant a- packing-house of their own. In most cases 
such shippers have old and especially favorable connec- 
tions in certain markets where their reputation is high and 
their old customers secure. Independent shippers usually 
have some special or unique advantage which relieves 
them, to an extent, from the common vicissitudes of the 
market. The chief stockholder in a large hotel in Chicago 
or Boston, for instance, who owns a winter home in an 
orange grove in California, will naturally ship his fruit to 
his own hotel for consumption. 

Independent associations are groups of small growers 
who have united together in building a cooperative pack- 
ing-house, yet who for some reason have not affiliated with 
the Exchange, but sell their fruit through commission men 
in the various markets. Many of these associations who 
think they are doing a little better outside the Exchange 
would quickly join and support the Exchange should it 
ever appear in danger of failure through lack of support. 
They prefer for the present, perhaps, to sail in the calm 
water close under the lee of the Exchange. 

THE CALIFORNIA FRUIT GROWERS' EXCHANGE 

This great cooperative organization of growers is the 
child of necessity. The season of 1892-93 was particu- 
larly disastrous as far as turning fruit into money was 
concerned, and the market conditions and arrogance of 



346 Citrus Fruits 

the railroads were intolerable. Accordingly the Southern 
California Fruit Exchange was organized in Los Angeles 
on October 2, 1895, in order to provide certain marketing 
of the fruit by more uniform methods. Ten years later the 
name of the organization was changed to the present title. 

The California Fruit Growers' Exchange has its home 
office in the Consolidated Realty Building in Los Angeles. 
Its organization is tersely described by G. H. Powell, the 
General Manager, 1 as follows : 

"The California Fruit Growers' Exchange is an organi- 
zation which acts as a clearing house in providing the 
facilities through which 6500 growers distribute and mar- 
ket their fruit. There are three foundation stones in the 
exchange system — the local associations of growers, the 
district exchanges, and the central exchange. The local 
associations, the district exchanges, and the central or 
California Fruit Growers' Exchange are organized and 
managed by the growers on a non-profit cooperative 
basis, each of them operating at cost, and each distribut- 
ing the entire net proceeds to the growers after operat- 
ing expenses are deducted." 

The local exchange. — "The California Fruit Growers' 
Exchange comprises 115 local associations, each of which 
has from 40 to 200 members. The growers usually organ- 
ize as a corporation without profit, under the laws of Cali- 
fornia, issuing stock to each member in proportion to his 
bearing acreage, to the number of boxes he ships, or in 
equal amounts to each grower. The association assembles 
the fruit in a packing-house, and there grades, pools, packs, 
and prepares it for shipment. The associations are man- 

1 California Cultivator, March 13, 1913. 



Marketing 347 

aged by a board of directors through a manager and are 
conducted exclusively for the benefit of the growers. 
They declare no dividends and accumulate no profits. 
The fruit is pooled each month, or for a shorter period, each 
grower receiving his proportion of the proceeds received 
for each grade shipped during the pool. Many of the 
associations pick the fruit, and some of them prune and 
fumigate the trees for the members. Each association 
has brands for each grade, and when a carload is ready 
for shipment it is marketed through the district exchange, 
of which the association is a member, through the agents 
and facilities provided by the California Fruit Growers' 
Exchange." 

The district exchange. — "There are seventeen district 
exchanges. These exchanges are corporations without 
profit. There may be one or more district exchanges in a 
community, depending upon the number of local associa- 
tions and other local conditions. The district exchange 
acts as a clearing house in marketing the fruit for the asso- 
ciations through the California Fruit Growers' Exchange 
and acts as a medium through which most of the business 
relations between the exchange and the local associations 
are handled. The district exchange orders cars and sees 
that they are placed by the railroad at the various associa- 
tion packing-houses ; keeps record of the cars shipped by 
each association, with their destinations ; informs itself, 
through the California Fruit Growers' Exchange, of all 
phases of the citrus marketing business; places the in- 
formation before the associations ; receives the returns for 
the fruit through the central exchange, and returns the 
proceeds to the associations." 



348 Citrus Fruits 

The central exchange. — "The California Fruit Growers' 
Exchange is a non-profit corporation under the laws of 
California. It is formed by 17 district exchanges, with a 
paid-in capital stock of $1700. It is managed by a Board 
of 17 directors through a general manager, one director 
representing each district exchange. The function of the 
California Fruit Growers' Exchange is to furnish market- 
ing facilities for the district exchanges at a pro-rata share 
of the cost. The exchange places bonded agents in the 
principal markets of the United States and Canada, defines 
the duties of the agents, and exercises supervision over 
them. It gathers information through them of conditions 
in each market, receives telegraphic advices of the sale 
of each oar, and furnishes the information every day in 
bulletin form to the local associations. The exchange 
business is on a cash basis ; it makes prompt accounting 
of returns to the growers through the district exchanges ; 
takes care of litigation that arises in connection with 
the marketing of the fruit ; handles all claims ; conducts 
an extensive advertising campaign to increase the demand 
for citrus fruit ; develops new markets and performs such 
other functions as are set forth in the contract between 
the central exchange and the district exchanges. The 
central exchange levies an assessment against each district 
exchange for a pro-rata share of the expense on the basis 
of the number of boxes shipped. It declares no dividends. 
It does not buy or sell fruit or any other commodity, and 
exercises no control either directly or indirectly over sale 
or purchase. Its function is to provide facilities for the 
distribution and marketing of the fruit for those shippers 
who desire such facilities. Under the exchange system 



Marketing 349 

every shipper reserves the right to regulate and control his 
own shipments ; to develop his own brands of fruit ; to 
use his own judgment as to when and in what amount it 
shall be shipped, and the price he is willing to receive, 
reserving the right of free competition with all other 
shippers, including the members of the same organization, 
uncontrolled by any one. The agent in the market acts 
directly under the order of the shipper, who determines 
the prices at which each car shall be sold outside of the 
auction markets, and all other matters connected with its 
distribution, the California Fruit Growers' Exchange 
acting as the medium through which orders pass from the 
agent to the shipper, but never selling a car or determining 
the price at which the fruit shall be sold. 

"The exchange is a democratic organization; the 
growers exercise control over all matters. Membership 
in the exchange is voluntary ; a grower may withdraw 
from an association at the end of a year ; an association 
may withdraw from a district exchange, and a district ex- 
change may withdraw from the central exchange, — these 
relations being set forth in the various contracts that hold 
the members together. There is no attempt on the part 
of the central exchange to regulate shipments, to eliminate 
competition, divide the territory or business, or to influ- 
ence prices. In this connection its functions are to keep the 
associations informed daily regarding the shipments from 
the state ; the general movement of exchange cars, the 
general conditions of the different marketing points ; the 
prices at which the exchange fruit is sold ; and in furnish- 
ing such other information as will allow the growers and 
shippers through their association and district exchanges to 



350 Citrus Fruits 

decide the questions of distribution and marketing for 
themselves. 

" One third of the entire shipments are sold at public 
auction, the remainder through unrestricted private com- 
petition. There is no uniformity in price in the different 
brands, because the fruit in each section, on account of 
the soil and other local conditions, has an individuality 
of its own, and every brand sells on its own merits. 

"The exchange is organized into several divisions; 
sales, legal, traffic, advertising, insurance, and mutual 
protection, and a supply department which furnishes the 
materials used in the packing-houses and on the ranches, 
at cost to the members. The exchange does not consign 
fruit. It is shipped on order ; sold f . o. b. ; or sold ' de- 
livered, subject to usual terms.' The exchange maintains 
district managers in all of the important cities of the 
United States and Canada. These employees are exclu- 
sively salaried agents, engaged only in the sale of fruit, 
in the development of markets, and in handling the local 
business problems of the exchange." 

The money received by the selling agents for fruit is 
deposited by them in national banks to the credit of the 
central exchange, which forwards it to the district exchange 
and is by them distributed to the growers. The exchange 
has collected more than one hundred and thirty-nine 
millions of dollars in addition to freight charges for citrus 
fruits in the last ten years, and the losses from bad debts 
to date have been less than seven thousand dollars. The 
exchange returns (f. o. b. California) for fruit shipped 
in the season 1913-14 were about eighteen million dollars. 

The exchange carries on two forms of advertising. 



Marketing 351 

Space in daily newspapers in all important cities is bought 
to the extent of $200,000 or more a year. In order to 
secure the chief benefits of this advertising for the members 
of the exchange, who pay for it, there has been devised a 
special quality brand known as " Sunkist " (see Fig. 112), 
the copyright for which is owned by the exchange. This 
brand is used by all exchange associations as an addi- 
tional sticker placed on their best brands only. The 
tissue paper wrappers used on fruit under this brand bear 
the "sunkist" emblem and such wrappers are redeemable 
in part payment for table silverware. This ware is triple 
plated and of good quality and bears a special orange 
design. In 1912, 1,750,000 pieces of silverware were dis- 
tributed in return for orange and lemon wrappers, and the 
exchange has become the largest single buyer of this class 
of silverware in the world. In the Chicago office, forty 
mailing clerks are required to take care of this business. 

The expense of maintaining the exchange, including 
advertising and every other expense, has never been as high 
as 3 per cent of gross sales, while ordinary commission and 
brokerage charges of other agencies vary from 5 to 10 per 
cent for selling alone. In 1914 the total cost of selling, 
including advertising and the maintenance of the sub- 
exchanges, amounted to 6y o^- cents a box. 

It is not a difficult matter to organize an association. 
The money required for incidental and organization ex- 
penses will be supplied by the membership fees of five or 
ten dollars. The money required for building the packing- 
house and beginning work is usually borrowed from the 
banks on association notes personally indorsed by the 
directors. When the sale of fruit begins a small amount 



352 Citrus Fruits 

to the box is held back with which to gradually pay off 
the notes. When real property, such as a packing-house 
and site, is acquired it may be mortgaged for as much as 
possible in order to relieve the directors of personal liabil- 
ity on the first notes issued. The membership fee should 
be kept low in order that new members may join at any 
time as old members drop out for one reason or another. 
Most associations desire as large a membership as possible, 
as it is more economical to pack fruit in large quantities 
and in a large, well-equipped house. 

Every association should act squarely and honestly with 
its customers. Special markets should be developed and 
fruit of uniformly good grade shipped regularly to those 
markets regardless of fluctuation in prices. It is usually poor 
policy to chase high prices by changing quickly from one 
market to another. It should be the ambition of each as- 
sociation to develop a high repufation for its brands of 
fruit on certain markets and then stay by those markets 
through the season, always striving to give good values and 
please the old customers. 

" The distribution of the oranges and lemons of each 
grower must be uniform throughout the year on a mer- 
chandizing basis ; neither the grower nor shipper can af- 
ford to speculate on the market. The fruit should go 
forward naturally from each grove during the period when 
it possesses the best quality for that district. Regular 
distribution increases consumption ; stabilizes the business 
of the shipper, the jobber, and the retailer. It furnishes 
the consumer a supply at the lowest average return be- 
cause the product is handled by every one at a reasonable 
distributing profit. The distributing cost of citrus fruit 



Marketing 353 

after it reaches the jobber, like many other food products, 
represents approximately 45 per cent of the consumer's 
cost. Erratic, speculative distribution increases the dis- 
tributing costs ; it results in a lower price to the producer 
and a higher cost to the consumer." ' 

Some years ago the citrus growers of Florida sent a 
committee to California to study the methods of the Cali- 
fornia Exchange. As a result of this the Florida Citrus 
Exchange was organized in the fall of 1909, and is now a 
successful organization. About 22 per cent of the Florida 
Crop of 1913-14 was handled through the Exchange. 

Citrus Protective League of California 

This is a voluntary organization formed in March, 1906, 
by representatives of growers, shippers, and shipping or- 
ganizations in nearly all of the citrus growing localities 
of the state to handle the public policy questions that 
affect the industry as a whole. Its purpose is to represent 
the grower and shipper in handling such questions as : 
railroad rates and transportation problems ; customs 
tariffs and other governmental relations ; state and 
federal legislation that applies directly to the business, and 
all other questions of a general nature that affect the up- 
building of the industry, except the marketing of fruit. 

The League is directed by an Executive Committee of 
nine and by a secretary and manager, the Executive Com- 
mittee having been appointed by an Administrative Com- 
mittee of thirty of the principal growers and shippers 

1 Report of G. H. Powell, General Manager, California Fruit 
Growers' Exchange, 1914. 
2a 



354 Citrus Fruits 

who act as a governing committee, and who were selected 
from the representative delegates who organized the 
League in 1906. The League represents about 90 per cent 
of the growers and shippers of the state, and is supported 
by funds raised by general assessment based on the num- 
ber of cars of fruit shipped by each member during the 
preceding year. 

In conclusion it may be well to point out that during the 
last decade the citrus fruit acreage in California has more 
than doubled. From 1900 to 1914 the size of the crop 
increased 254 per cent. In order that consumption may 
keep pace with this rapid increase in production, it is 
extremely important that the growers loyally support the 
organizations which are developing a comprehensive, 
economical, and efficient system for distributing, selling, 
and advertising. citrus fruits. 

It is also highly important that a profitable by-product 
industry be established. A means of disposing of low- 
grade fruit at home will do more than anything else toward 
keeping such fruit from glutting the markets and depress- 
ing the prices of fancy fruit. This is bound to result in 
an improvement in the grades of fruit shipped to market, 
with consequent marked increase in consumption. 



CHAPTER XX 

PROFIT AND LOSS 

If the question is asked, " Does citrus culture really 
pay?" we are compelled to answer "Yes and no." It 
pays handsomely where proper conditions are combined 
with knowledge, industry, common business sense, and 
capital. It does not pay in many cases where these things 
are not combined. Some persons make very large, almost 
fabulous, profits growing citrus fruits, and these examples 
are widely quoted by real estate agents and land boomers. 
Other persons lose money consistently year after year. 
When we consider the total production of any crop in the 
United States, such as corn, wheat, or cotton, we find the 
average yield an acre is surprisingly low. Citrus fruits 
are no exception to the rule. The Citrus Protective League 
has collected a great deal of data on the cost of production 
of citrus fruits, and Victor Newland, a student at the Uni- 
versity of California, has worked out the average prices 
received. Such large collections of figures should not be 
taken too seriously, yet they possess considerable indica- 
tive value. It appears that the average box of oranges 
for the five years preceding 1913 returned a net profit of 
15 cents to the grower, while the average box of lemons 
produced during the same period returned a loss of about 

355 



356 Citrus Fruits 

20 cents. And yet skillful growers, have commonly made 
much higher profits on lemons than on oranges, and a good 
bearing lemon grove will sell for more money to-day than 
an orange grove of similar age. This means that there 
have been a larger proportion of failures with lemons than 
with oranges. 

There are, of course, many reasons why some citrus trees 
fail to pay. Some trees are planted with the object of 
producing fruit ; while others, we regret to have to say, 
have been planted for the purpose of making it easier to 
sell the land. There is a great deal of land that will grow 
a beautiful young tree for a few years, but upon which 
bearing trees will soon fail. A considerable acreage of 
either very questionable or impossible citrus land has been 
planted out in large blocks and then divided up and sold 
to unwary investors, who in most cases are inexperienced 
persons newly arrived from other parts of the country. 
Much citrus acreage is sold by mail to absent buyers, a very 
bad practice. It is strange how many unsophisticated 
persons there are in Northern cities who will trustingly 
send their money by mail to some agent with the request 
that he "Be sure to select a nice orange grove for them." 
Where there is such an absolute lack of business sense as 
this, it is not surprising that there are so many failures. 

Absentee ownership is one of the banes of the citrus 
business. If a person cannot visit his property at least 
once a month and look after the various operations in per- 
son, he should sell out to some one who can. 

Another trouble is over-capitalization, which is encour- 
aged by speculation. Many beautiful towns and cities 
have been built literally in the orange groves and the in- 



Profit and Loss 357 

crease in value of the land for residence and other pur- 
poses has increased the capital and taxes to a point where it 
becomes difficult to make any but the most expertly man- 
aged citrus orchards pay. 

Many orchards are composed largely of degenerate 
types of trees ; many have been ruined by the mottled- 
leaf disease ; and many are too frequently visited by frost. 

Let us not dwell too much on the dark side, however, but 
hasten to give assurance that any one with sufficient capi- 
tal, a reasonable knowledge of horticultural operations, 
and ordinarily good business judgment may easily make 
a good profit raising citrus fruits, provided he or she is 
careful to see that the following requirements are satisfied : 

1. A location in a proved citrus district, reasonably 
free from frosts and winds and within hauling distance of a 
packing-house. 

2. An easily worked, fertile, well-drained, deep soil, 
purchased at a reasonable price. 

3. An ample supply of good water. 

4. Strong, thrifty, clean trees grown from carefully 
selected buds of standard varieties. 

5. Proper preparation of ground and planting of trees. 

6. Personal care of the trees with conscientious culti- 
vation, irrigation, fertilization, and pruning. 

7. The exclusion of scale insects and proper treatment 
for fungus and other diseases. 

8. Membership in a local cooperative marketing asso- 
ciation. 

These may be called the eight fundamental require- 
ments for success. Failure in any one of these require- 
ments may bring about the failure of the grove, although 



358 Citrus Fruits 

failure does not necessarily follow in every case. On the 
other hand, if each of these requirements is fairly met, 
success is as sure as almost any horticultural venture can 
be. In addition to these things it is advisable for the be- 
ginner to cooperate with the neighbors toward the general 
good of the district by joining loyally in fumigating and 
frost righting campaigns. The College of Agriculture 
should be freely consulted, and the beginner will usually 
find it to his advantage to enroll for the free correspond- 
ence course in citrus fruits conducted by the College. 

CAPITAL REQUIRED 

The next question to be considered is, " How much 
money will be needed to meet the eight requirements for 
success outlined above ? ' ' This question permits of no defi- 
nite answer on account of the very wide variations in costs 
in different localities and under different conditions. In 
some localities good citrus land may still be had at $150 
an acre, while in other districts it may be considered cheap 
at $500 an acre. 

Water also varies very widely in cost. In some locali- 
ties where there is comparatively little frost, combined 
with good soil and other natural advantages, the cost of 
water has soared surprisingly high. After the local 
supply has all been appropriated, additional water is 
often brought from great distances. This is usually 
accomplished by forming a water company which pur- 
chases sufficient water bearing lands and installs the 
necessary pumping plants, tunnels, and aqueducts. The 
necessary amount of water stock in such a company 



Profit and Loss 359 

(which is the water right) sometimes costs as much as $200 
an acre and the annual assessments for pumping expense 
and repairs may be as much as $40 an acre a year. 

The following estimate gives some general idea of the 
cost of bringing a young grove into bearing in the San 
Gabriel Valley : 

Cost of Bringing a Ten Acre Orange Orchard to Bearing 

10 acres orange land $1500 

Clearing and grading 2000 

Water right 1500 

Trees, 1000 @ $1 1000 

Planting trees at l\i each 75 

Irrigating system 200 

Irrigating and cultivating, 5 years .... 2000 

Taxes and incidentals, 5 years 250 

Fertilizer, 3 years 250 

Pruning 200 

Total expense $8975 

Returns from fruit less packing charge, 3 years . . . 1200 

Total investment at beginning of 6th year . . . $7775 

A well managed orange orchard in full bearing ought 
to yield 250 packed boxes an acre. Many orchards aver- 
age much more than this amount. The cultural, packing, 
and selling costs ought not to exceed $2.00 a box. The 
average selling price for oranges for the last five years has 
been about $2.80. 

At the time the reduction of the tariff on citrus fruits was 
under discussion in Congress, the Citrus Protective League 
made an extensive investigation of the cost of producing 
oranges and lemons. The publications of the League con- 
tain some very extensive tables showing all items of cost 
in great detail, from which the following figures are taken : 



360 Citrus Fruits 



Data on 26,000 Acres of Oranges 

Average cost of materials an acre $83.24 

Average cost of labor 52.82 

Average cost of crop an acre $136.06 



Data on 4,186,983 Boxes of Oranges 

Cost per Box 

Picking $.0771 

Hauling 0287 

Packing 3246 

Picking, hauling, and packing $.4304 

Cultural cost .8633 

Freight 828 

Refrigeration .0789 

Selling and collecting .07 

Total cost laid down in market $2.2706 

Data on 1,391,711 Boxes of Lemons 

Cost per Box 

Cost of growing $1,000 

Cost of picking .253 

Cost of hauling 039 

Cost of packing .596 

Cost of freight 840 

Cost of refrigeration .026 

Cost of selling .070 

Total cost laid down in market $2,824 

In estimating the amount of capital required to conduct 
a bearing citrus orchard for a year, the following figures, 
also taken from the League reports, may be found of value. 
The cost of superintendence, administration, and depre- 
ciation are omitted : 



Profit, and Loss 



361 



Cost of Operating Bearing Grove an Acre a Year of 



Cultivating 

Pruning 

Irrigating 

Fumigating (materials and labor) when 

necessary 

Spraying (when necessary) 

Spreading fertilizer 

Other tree care (propping, caring for sick 

trees, etc.) 

Chemical fertilizer 

Barnyard manure (when used) .... 

Water 

Forage and grain (feed for work stock) . 

Taxes 

Maintenance and repairs 

Incidentals 

Frost protection (when used) 



Oranges 



$18.00 
8.00 
7.50 

18.00 
7.50 
2.50 

3.00 
30.00 
30.00 
18.00 
20.00 
12.00 
7.00 
2.50 
30.00 



Lemons 



$20.00 
22.50 
12.00 

20.00 
7.50 
2.50 

5.00 
35.00 
30.00 
20.00 
20.00 
10.00 
7.00 
2.50 
40.00 



The above columns of figures are not added for the 
reason that no orchard requires all of these expenditures 
in any one year. The same orchard would not be fumi- 
gated and sprayed, and manure would not be applied every 
year as sufficient supplies are not available. These figures 
are also open to the objection that they represent averages 
between different districts and hence are not strictly typi- 
cal of any one district. Inasmuch as they are susceptible 
to such wide variations, they should be accepted as rough 
approximations only. See also statement No. 1 on pages 
162 and 163. 

The Citrus Protective League has published the follow- 
ing figures on average yields including all varieties of or- 
anges and lemons. 



362 



Citrus Fruits 



Year 


Oranges ave. 

26,000 Acres 

Boxes per Acre 


Lemons ave. 

6137 Acres 

Boxes per Acre 


1906-7 

1907-8 

1908-9 

1909-10 

1910-11 

Average for 5 years 


150.1 
129.5 
167.2 
136.7 
191.0 
157.6 


149.1 
187.1 
220.9 
196.1 
211.2 
196.2 



The average f.o.b. price received for oranges for the 
last ten years is about -$1.50 per box and for lemons $2.00 
per box. 



JUDGING ORCHARDS AND LANDS 

It is poor policy to examine a piece of prospective land 
or a bearing orchard without a program. This is espe- 
cially true when different propositions are to be contrasted 
with a view to deciding on a purchase. Many inexperi- 
enced people buy land without digging into it, but this 
practice cannot be too strongly condemned. In arid 
countries surface indications are not reliable guides as to 
what may be expected below the surface. Holes should 
be dug at least six or seven feet deep in various places and 
the soil examined for changes in character, hardpan, 
stone, and so on. 

It is suggested that the following list of points be used 
in going over every piece of land. Each point may be 
weighted after the fashion of a score-card and thus accurate 
comparisons between different propositions made easier. 



Profit and Loss 363 

Score-card for Citrus Land 

1. Freedom from frost, 
r 2. Water ; legal right, amount, quality, cost. 

3. Kind and quality of soil. Topography. 

4. Continuity of tract and freedom from waste land. 

5. Freedom from stones and brush. Cost of clearing 
and grading. 

6. Freedom from hardpan. 

7. Freedom from alkali. 

8. Drainage outlet. 

9. Susceptibility to wind. 

10. Distance from scale infested orchard. 

11. Nearness to town. 

12. Nearness to packing-house and railroad siding. 

13. Quality of roads. 

14. Price per acre. 

Additional Points for Bearing Groves 

15. Uniformity and yield record of trees. 

16. Freedom from scale insects. 

17. Freedom from mottled-leaf and other diseases. 

18. Condition of trees as to pruning and general care. 

19. Adaptability of variety to district. 



CHAPTER XXI 

DISEASES AND THEIR CONTROL 

Citrus trees are susceptible to a large number of dis- 
eases, some of which are due to the attacks of parasites 
and some to physiological derangements of nutrition. 
Practically all of the fungus diseases have been investi- 
gated by scientists and are fairly well understood, while 
comparatively little progress has been made in the study 
of physiological diseases. In Florida and some other 
humid citrus growing regions the fungus troubles are most 
common, while in California and other places where the 
climate is more or less arid the fungus troubles are less 
abundant and derangements of nutrition due to unfavor- 
able soil conditions, alkali, excessive heat, and perhaps 
to excessive illumination and transpiration are very fre- 
quently met with. 

GUM DISEASES 

Citrus trees are apt to excrete gum from a number of differ- 
ent causes, some of which fall in each of the classes mentioned 
above. 

Broion Rot Gum-Disease 

Among citrus growers this trouble is usually known simply 
as "gum-disease." Until recently it was thought to be due 

364 



Diseases and their Control 



365 



solely to physiological causes. H. S. Fawcett has now 
shown that the true cause is none other than that old enemy 
of' the citrus grower, the brown rot fungus Pythiacystis 
citrophthora. 

Brown rot gumming 
is most common on 
lemon trees and is 
characterized by a 
copious exudation of 
gum from the trunk 
just above the bud 
union. A certain area 
of bark surrounding 
the gum dies, becomes 
hard and dry with no 
outer evidence of fun- 
gus growth, and is 
often pushed slightly 
away from the cam- 
bium by the pressure 
of the rapidly forming 
gum. This kind of 
gum-disease may be 
largely prevented by 
avoiding the soil con- 
ditions most favorable 
for the growth of this soil-inhabiting fungus. No water should 
be allowed to stand in contact with the trunk. Heavy or 
adobe soils should be kept well worked under the trees and 
prevented from being mounded against the trunks. It will 
do no harm to draw the surface soil away from the trunks, 
even exposing the crown roots, provided the irrigation water 
is prevented from running into the basin thus formed. 




Fig. 128. — The Fawcett method of treat- 
ing gum-disease. Note types of scrapers. 



366 Citrus Fruits 

The fungus gains access to the tree either through abrasions 
of the bark or directly through the lenticels or breathing 
pores. The bark of the sour orange is very resistant to in- 
fection and trees budded six or more inches high on sour 
stock are quite resistant. 

When a case of brown rot gumming is discovered, the tree 
trunk should be treated by cutting away every particle 
of diseased bark and painting the trunk with bordeaux 
mixture paste, made as follows : one pound of bluestone 
and two pounds of unslaked lime with water to make a 
thick whitewash. It is advisable on all heavy, fungus infested 
soils to apply this paste as a preventive to all healthy trees 
so situated as to be liable to gum-disease. This treatment 
should be repeated every second year at least. 

Botrytis Gumming 

Another form of gum-disease is caused by the fungus 
Botrytis vulgaris and is fairly common on old lemon trees 
growing on low, heavy soils. It occurs on the trunks and 
is characterized by a much less copious flow of gum but a much 
more general infection. The outer bark becomes soft and 
dies gradually from the outside inward, differing radically 
in this respect from the brown rot gumming. In moist 
weather the disease is accompanied by cushions of small 
dark gray fruiting bodies scattered over the surface of the 
dead bark. 

The proper treatment is to scrape off the outer dead bark, 
leaving the inner bark wherever it is alive, and applying the 
bordeaux paste. Special tools have been developed for 
scraping and they should be kept in the bucket of paste when 
not in use. The application of bordeaux paste to healthy 
tree trunks is suggested as a good preventive for this 
disease. 



Diseases and their Control 367 



Scaly-bark 

The sweet orange alone is subject to this form of gumming 
which occurs in patches quite generally over the trunk and 
large limbs to a considerable height. In this case the outer 
bark breaks and comes away in small, dry scales, leaving the 
living bark underneath with a rough and noduled appearance 
and with a large number of small gum pockets which exude 
only a small amount of gum. In severe cases, the infected 
tree or branch drops its leaves, and after languishing for a year 
or two, finally dies. In some cases, large vigorous trees may 
support a few scaly-bark patches for many years without 
any serious reduction in crop. While this disease has been 
investigated for a number of years, the cause has not yet 
been discovered, and no satisfactory treatment is known. 
Where the disease occurs only on the branches, they should 
be cut off below the diseased area and burned. Where 
the disease occurs on the trunk, it is advisable to scrape the 
bark thoroughly and apply bordeaux paste, inasmuch as in 
certain instances this has appeared to be of some value. 

Twig Gumming 

Young trees and nursery stock are sometimes affected with 
gumming of the twigs which is apparently caused by copious 
irrigation when the soil has become too dry. The gum 
breaks out along the small twigs all over the tree with splitting 
of the bark, dropping of leaves, and dying back of twigs. 
Vigorous trees always recover and the trouble may be pre- 
vented by giving due attention to regular irrigation. Some- 
times this form of gumming is caused by a period of desic- 
cating north wind. Such winds do not affect the mature 
wood, but often cause the bark to split and drops of gum 
form on vigorous young shoots. 



368 Citrus FrUits 

Leaf Gumming 

This is very common, especially on orange trees, in hot 
localities. Dark reddish colored, slightly raised spots or 
areas appear on the leaves in places where they have been 
turned up and the under side exposed to the sun or frost. 
These spots are formed by the secretion of a gum-like sub- 
stance in the tissue just under the epidermis and are simply the 
result of sunburn or frost injury at a time when the leaves are 
young and tender. The trouble is not serious and need not 
be feared. 





Fig. 129. — Reddish gum areas on under side of leaf caused by sunburn. 

Gumming of Seed Bed Stock (Pythiacystis citrophthora) 

It often happens that the brown rot fungus, becoming 
established in the soil used for seed beds, will infect large 
numbers of sweet orange seedlings, especially where the soil 
is allowed to become too wet. Many of the seedlings are 
girdled at the surface of the ground and entirely ruined and 
have to be discarded when the plants are dug for sale. Sour 
orange plants are somewhat more resistant, but even they 
will sometimes show a considerable amount of gumming, 
as immunity to the brown rot fungus is not fully acquired 
until after the plants have been transferred to the nursery row. 



Diseases and their Control 369 

In order to prevent this trouble, the surface soil should be 
kept as dry as the health of the plants will permit. When 
the first indication of disease is noticed, the beds should be 
thoroughly sprayed with bordeaux mixture, applying the 
liquid in quantities sufficient to drip down and moisten the 
entire surface of the soil. 

Exanthema or Die-back 

This disease was first described as occurring in Florida in 
1875 and has since assumed great economic importance, 
having appeared in every citrus growing district in that 
state. The annual losses directly attributable to exanthema 
are very heavy. 

In California and Arizona, however, the losses sustained 
from the effects of this disease have been comparatively 
light. It has been reported from several localities in southern 
California, but in very few cases has the outbreak been 
widespread or sufficiently severe to attract very much atten- 
tion. 

There is a widespread misunderstanding in regard to the 
term "die-back." There is of course a dying back of the 
branches due to any one of a very large number of causes, 
such for example as mottled-leaf, cottony-mold fungus, frost, 
and the like. Seeing dead twigs in their trees, many persons 
are apt to jump to the conclusion that the trouble is die-back, 
which presents itself to their minds as a vague though no 
less terrible malady, the symptoms of which they do not 
clearly understand. The term "exanthema" is a Greek 
word meaning an eruption or pustule which was given to 
this particular disease by Swingle and Webber in 1896 and 
is much to be preferred to "die-back." There is only one 
exanthema but there may be many kinds of die-back. 

Exanthema has more symptoms than almost any other 
2b 



370 



Citrus Fruits 



plant disease, and there is little excuse in failing on a diag- 
nosis. The first indication of exanthema appears as an ab- 
normally dark green color of the leaves near the center of 

the tree. This is followed by a 
dying back of the young growth 
with the formation of small 
swellings or gum pockets at the 
nodes. These often crack open 
and tears of gum are exuded 
from the very young twigs, while 
the cracks on larger twigs appear 
filled with a red or brown 
gummy substance. Often af- 
fected twigs will attempt a new 
growth but succeed only in form- 
ing clusters of sickly, pale 
colored buds in the axils of the 
leaves. Water sprouts often 
arise from healthy wood below 
the diseased tissue, which in turn 
may or may not become affected. 
The fruit on badly affected 
branches either falls or remains 
small and pale yellow in color. 
Usually the fruit which reaches 
some size exhibits a very char- 
acteristic dark brownish red 
stain which appears as irregular 
patches of gummy material laid 
over the surface . These red areas 
are usually slightly elevated, and badly affected fruit often 
splits open longitudinally while hanging on the tree. Affected 
fruit is usually abnormally thick skinned, contains numerous 




Fig. 130. — Exanthema pustules 
on Valencia orange twigs. 



Diseases and their Control 371 

gum pockets at the center, and in the case of oranges has an 
insipid sweet taste. In many cases exanthema is accom- 
panied by mottled-leaf, although this is probably merely a 
coincidence, as there is no known connection between the two 
diseases. Exanthema is most common on the orange al- 
though it has been found by the writer on both lemon and 
pomelo. 

From all its appearances exanthema would naturally be 
supposed to be a fungus disease, but this appears not to be the 
case. A great deal of scientific investigation has been ex- 
pended, but as yet no fungus or other parasite has been found 
connected with the trouble. Experiments have shown 
moreover that the disease can be produced in healthy plants 
without the aid of any parasite whatever. For these reasons 
it is considered to be a physiological derangement of the 
vital functions caused by irregular or improper food and 
moisture supply ; in other words, a form of plant indigestion. 
Citrus plants appear to be especially susceptible to various 
forms of malnutrition. 

In Florida the cause of this condition has been fairly well 
established. It has been found to be due to an excess of 
ammonia in the soil resulting from applications of stable 
manure or other form of organic nitrogen. Florida growers 
are almost certain to have exanthema if they apply large 
amounts of dried blood or cottonseed meal, or plant the trees 
on land previously occupied by cattle pens or chicken yards. 
By being scrupulously careful to avoid these things Florida 
growers have been able to reduce the amount of exanthema 
to a minimum. 

In California, however, the conditions are very different. 
Here growers apply organic manures in very large amounts 
with apparent impunity, as far as exanthema is concerned. 
Why this marked difference should exist is certainly a mys- 



372 Citrus Fruits 

tery, but it exists nevertheless. The chief causes of exan- 
thema in California are improper soil drainage and faulty 
soil structure ; or as Lipman has recently suggested, the direct 
cause may be an abnormally slow nitrification in the soil 
accompanied by abnormally rapid ammonification, thus forc- 
ing the plants to take up ammonia compounds. 

Exanthema may be cured entirely by the removal of the 
conditions causing the trouble. Where ground water is the 
cause, the land may be drained, but where an open porous 
subsoil allows the water to pass down, but on account of its 
open nature does not permit the return of the water by capil- 
larity, the remedy is very difficult or impossible. Such lands 
should not be planted to citrus fruits. 

Mal-di-gomma or Foot-rot 

In European citrus districts as well as in Florida foot-rot 
has caused heavy losses. In California, however, it is com- 
paratively rare. It is thought to be caused by a fungus 
of some kind which produces rotting of the roots quite 
distinct from that described above. The decay starts 
in the bark of the main roots, which becomes soft and 
slimy, and gradually spreads from the surface of the ground 
downward. This is accompanied by a yellowing and drop- 
ping of the leaves in that part of the top directly over the 
diseased roots. When disturbed, the rotten roots have a 
peculiar and offensive odor. 

Lemon roots are quite susceptible, sweet orange somewhat 
less so, while sour orange is quite resistant. Apparently 
the only conditions under which the disease can exist are 
extremely poor drainage and very wet, heavy soil about 
the roots. Badly diseased trees are difficult to revive but 
may be replaced provided the soil conditions are improved. 



Diseases and their Control 373 

The use of sour orange stocks together with good drainage 
and aeration of the soil are the best methods of prevention. 

Toadstool Root Rot 

Most mushrooms grow only on dead material but there are 
some which are actually parasitic on living plants. The 
mushroom known as ArmiUaria mellea has caused heavy 
losses of fruit trees both in Europe" and America. The 
fungus is native to the roots of oak and some other trees and 
occurs most commonly on lands previously occupied by oak 
trees. After the oak trees are cut down, the fungus lives 
forsome years on the dead roots in the soil and should citrus 
trees be planted on the land at once, their roots are very likely 
to become infected. The fungus usually kills the tree in 
from two to four years, although in some instances diseased 
trees may remain alive, though unprofitable, for an indefinite 
period. In affected trees, usually only a part of the top dies 
at first, the dead branches gradually increasing in number. 
If the roots are examined, certain ones will be found decayed 
and soft. Just under the bark may be seen fan-shaped pieces 
of felty white fungus with the not unpleasant odor of fresh 
mushrooms. Soon after a root is attacked there may be 
seen along the side, and closely appressed to the bark, the 
rhizomorphs or long black strands of the fungus which re- 
semble hay wire, although very crooked. During prolonged 
periods of rainy weather, the fungus sends up from the 
diseased roots large clusters of a dozen or more toadstools 
which are brownish tan in color, six to ten inches high, and 
each one, where not crowded, three or four inches broad on 
top. ArmiUaria lives only on the roots of the trees and can- 
not remain for any length of time in soil which contains 
no tree roots. There is no danger (as some think) of in- 



374 Citrus Fruits 

creasing the spread of the fungus from tree to tree by appli- 
cation of barnyard manure. 

From the nature of this trouble it is apparent that no such 
remedy as spraying the foliage can have the least effect on 
the disease. There is at present no satisfactory remedy. 
It is not known whether sweet, sour, or pomelo root stocks 
are equally susceptible. It is urgently recommended that 
four or five years at least be allowed to elapse between the 
digging out of all oak roots and the planting of citrus trees, 
in order that the fungus may die out. During this time, the 
land may be planted to vegetables or alfalfa if water is 
available. 

Mottled-leaf 

For the past ten years a very peculiar and baffling disease 
of citrus trees has been gradually extending through southern 
California. It is known as mottled-leaf, and up to the present 
time has been considered to be a derangement of nutrition 
due to physiological causes. This disease is probably the 
most serious problem now before the California citrus 
growers. The injury to some of the finest orchards in the 
state has amounted to millions of dollars in the aggregate. 

Mottled-leaf is a kind of chlorosis of which there are several 
common on citrus trees. Mottled-leaf, however, is the only 
form which is widespread or very serious. The trouble 
first appears as light colored areas situated between the veins 
of the leaves. The contrast between the color of the veins 
and interspaces is very striking. Mottled leaves are found 
only towards the ends of the shoots and represent leaves 
in which the green color has never completely developed, 
rather than those in which the chlorophyll has once existed 
and then disappeared. Leaves which are once green never 
become typically mottled, although they may become lighter 



Diseases and their Control 



375 




Fig. 131. — Mottled-leaf disease on Eureka lemon. 



376 Citrus Fruits 

in color or even bright yellow, as in other forms of chlorosis. 
As the mottling increases there is a decided shortage in 
yield of fruit and in bad cases the fruit present is very 
small, and turns pale yellow or white when about an inch in 
diameter. There is considerable dying back of the branches 
and many sickly shoots put out along the trunk and large 
limbs. In a good many symptoms this disease is similar to 
peach yellows. 

Mottled-leaf affects all kinds of citrus trees, regardless of 
the kind of stock they are budded upon. It affects other 
trees also, including elm, maple, camphor, eucalyptus, and 
particularly Japanese privet. The disease occurs in many 
parts of the world, but apparently it has been seriously de- 
structive only in California. It is quite general in the 
Riverside-Redlands district, at Corona, Rialto, Bloomington, 
Pomona, and Covina. In San Diego, Ventura, and Santa 
Barbara counties it is much less severe. It occurs in parts of 
Tulare County. In the Sacramento Valley it is as yet ex- 
ceedingly rare in spite of the fact that many carloads of 
slightly mottled nursery trees from southern California have 
been set out. 

A great deal of scientific investigation and study has been 
put upon this disease and a great many theories have been 
advanced as to the cause. Up to the present time the true 
cause has not been definitely proven nor has a satisfactory 
remedy been clearly demonstrated. 

Some years ago the writer, working on the hypothesis 
that mottled-leaf, like peach yellows, might be transmitted 
by buds used in propagation, performed the following experi- 
ment : buds from badly mottled twigs of both oranges and 
lemons were inserted in healthy sour orange stocks. On ac- 
count of the weakness of the buds only a few grew, but these 
finally grew up into as healthy trees as any in the nursery. 



Diseases and their Control 



37' 



This showed that mot- 
tled-leaf is not trans- 
mitted by budding. 

In 1910 R. R. Snow- 
den * advanced the 
theory that mottled- 
leaf was due to an ex- 
cess of magnesia or an 
improper ratio be- 
tween magnesia and 
lime in the soil. 
Snowden showed that 
the soils of some 
healthy groves aver- 
aged about 2.5 parts 
of lime to 1 of mag- 
nesia, while the soils 
from sickly groves 
averaged 1.18 of lime 
to 1 of magnesia. This 
theory was much dis- 
cussed at the time, 
but subsequent study 
brought to light so 
many exceptions to 
the supposed rule that 
the theory was greatly 
weakened. Heavy ap- 
plications of lime 
moreover have by no 
means proved a cure 
for the disease. 




Fig. 132. — Advanced stage of mottled- 
leaf disease showing formation of mul- 
tiple buds. 



1 California Cultivator, Aug. 11, 1910. 



378 Citrus Fruits 

Some prominent citrus growers have held that starvation 
or a lack of humus in the soil is the cause of the trouble. In 
answer to this it may be said that some of the worst affected 
groves in the state are situated on apparently ideal soil 
and are among those best fertilized and otherwise well cared 
for. 

Mottled-leaf is much more prevalent on sandy and gravelly 
soils than on heavy adobe soils. In orchards where a certain 
area or streak of mottled-leaf runs through the orchard this 
usually corresponds to an area where the subsoil differs 
much from the top soil, usually being more coarse and open. 
This has led Smith 1 to conclude that " the most prevalent 
and typical form of mottled-leaf is due to an irregular supply 
of moisture and plant food." 

In 1912 J. R. Hodges, an horticultural inspector at Covina, 
California, noticed nematode worms in the soil near the 
roots of trees suffering from mottled-leaf. He advanced the 
theory 2 that the disease was caused by these nematodes. 
The matter was further investigated at the University of 
California Pathological Laboratory at Whittier where it 
was discovered that the nematodes were actually parasitic 
on the roots. E. E. Thomas of the laboratory staff 
published a preliminary report 3 on the distribution of nema- 
todes in the state and the possible relation between the worms 
and the disease. The nematode theory was by far the most 
plausible of any offered up to that time and at once attracted 
the attention of many scientists to the problem, which was 
now attacked from an entirely new angle. The name with a 
description of this nematode worm is given in Chapter XXIV. 

Several years will be required for the definite working out 

1 R. E. Smith, Cal. Sta. Bull. No. 218, p. 1139. 

2 Cal. State Com. Hort. Mo. Bull., Vol. II, No. 6, p. 555. 

3 University of Cal. Agr. Exp. Sta. Cir., No. 85, February, 1913. 



Diseases and their Control 379 

of the relation between nematodes and mottled-leaf. Mean- 
while a great deal of survey work is being done. The theory 
is still held in abeyance on account of the fact that the worms 
are not always found on the roots of mottled trees and they 
are occasionally found in small numbers on the roots of 
apparently healthy trees. Experiments are now being carried 
on with potted trees in sterilized soil which has been inocu- 
lated with the nematodes. 

In May, 1914, Kellerman and Wright l published the theory 
that mottled-leaf was commonly caused by nitrogen starva- 
tion following the plowing under of mature straw rather than 
a green cover-crop. It was explained that the mature straw 
contained large amounts of cellulose and that the molds and 
bacteria which decomposed the cellulose in the soil used up 
the available nitrate nitrogen present in the soil. They 
suggested further that in maintaining the humus of citrus 
soils, green, succulent materials be used rather than mature 
or dry straws. While this theory appears to be borne out by 
greenhouse experiments it is considered inadequate to ac- 
count for any large proportion of the mottled-leaf disease in 
California. 

Perhaps the most plausible theory yet offered is that 
recently published by Chas. B. Lipman. 2 It is explained 
that a poor nitrifying power on the part of the soil, with the 
ammonifying power remaining normal, may result in the 
change of practically all the nitrates in the soil to ammonia 
compounds. It is further , shown that while some plants, 
such as rice for example, prefer their nitrogen in the form of 
ammonia compounds, that such compounds are actually 

1 Jour. Agr. Research, Vol. II, No. 2, pp. 101-113. 

2 "The Poor Nitrifying Power of Soils a Possible Cause of 
Die-Back in Lemons." Science, n. s., Vol. XXXIX, No. 1011, 
May 15, 1914. 



380 Citrus Fruits 

poisonous to citrus trees, which show a decided preference 
for nitrates. With the condition in the soil favoring slow 
nitrification and rapid ammonification the trees are forced 
to take ammonia compounds or go without nitrogen entirely, 
as in many California soils the ammonia resulting from the 
decomposition of organic matter is actually set free in the air 
and lost entirely. Experiments are now being performed 
in the hope of finding a practicable method of treating 
orchard soils which may accelerate nitrification and at 
the same time retard ammonification. 




Fig. 133. — Spot on old lemon leaf due to wither-tip. 

Wither-tip (Colletotrichum gloeosporioides) 

This disease is said to be quite common in Florida and 
especially on limes in Cuba, causing a spotting of the old 
fruit and leaves, killing back the twigs, and causing the young 
newly set fruit to drop off. 1 In California, however, it ap- 

1 A recent investigation at the University of California has 
shown that in Cuba and Florida, two distinct diseases have been 
confused. The killing and deforming of young foliage and fruits 
of the lime are due to a fungus which somewhat resembles Colleto- 
trichum gloeosporioides but is entirely distinct from it. This 



Diseases and their Control 381 

pears to be of little practical importance, for although the 
fungus has long been present in abundance throughout the 
citrus growing areas, it very rarely attacks healthy trees 
as an active parasite. On senile leaves or young leaves 
weakened by fires, frost, fumigation, or otherwise, it causes 
dead spots, on the surface of which may be seen the minute 
black fruiting bodies of the fungus. The fungus occurs also 
on twigs weakened from any of the above mentioned 
causes. Trees suffering from gum-disease, foot-rot, gopher 
injury, alkali, or from other troubles, often show an abundant 
growth of wither -tip. Spraying with bordeaux mixture will 
reduce the amount of the fungus, but perhaps a more logical 
procedure would be to remove the causes of weakness and 
promote a healthy and disease-resistant growth. In certain 
rare cases, especially in very wet, cold weather and near the 
coast, it is possible of course that this fungus may occasion- 
ally act as a true parasite, in which case spraying with 
bordeaux mixture is a simple remedy. Certain very small 
red or salmon colored spots which sometimes occur on 
lemons in Ventura County have been found to be due to this 
fungus. 

It may be added that chiefly on account of its common 
name, "wither-tip," orchardists are very apt to refer to a 
large number of their tree troubles as wither-tip which are 
in no way attributable to CoUctotrichum gloeosporioides. 

new fungus has been called Gloeosporuim limetticolum. It causes 
a very injurious disease of limes and may attack lemons under 
artificial conditions but has not been known to do so under 
natural field conditions. Oranges and pomelos are not attacked. 
Extremely warm and humid atmospheric conditions are neces- 
sary for the development of the fungus, and it is not known to 
occur in California. See Clausen, R. E., "A New Fungus 
Concerned in Wither-Tip of Varieties of Citrus Medica," Phyto- 
pathology II, 6, 217, December, 1912. 



382 Citrus Fruits 

When lemons which have been grown in the warmer sec- 
tions are stored for a long time they finally break down with 
a soft rot at the center known in the packing-houses as " old 
age decay" or "core rot." The general exterior appearance 
of the lemons may be normal, but when pressed between the 
fingers they collapse. This decay is not yet clearly under- 
stood but is probably due primarily to the wither-tip fungus, 
which usually kills the buttons after they have been 
weakened by age. Later, as the fruit ages and becomes less 
resistant to encroaching organisms, a species of Alternaria 
penetrates the fruit by way of the dead button, following 
and turning brown the central core of pith and also the 
fibrovascular bundles as they radiate through the spongy 
tissue of the rind. The juice vesicles seem to be the last 
to be affected. After the vascular system is broken down 
the lemons lose their elasticity and appear dead to the 
touch. Fruit in such a condition should not be shipped, as it 
has very poor carrying qualities and decays very quickly when 
exposed for sale in warm weather. The chief remedy for 
this trouble is to avoid allowing the fruit to ripen on the 
trees, and to store in houses where the temperature may be 
accurately controlled. When the buttons succumb to wither- 
tip the fruit should be closely watched and hurried to market 
at the first indication that the fungus is entering the fruit. 

Twig blight (Sclcrotinia libertiniana) 

All kinds of ■ citrus trees sometimes exhibit a sudden 
withering and dying of small twigs and occasional branches 
up to one inch in diameter. The green leaves suddenly 
wither and remain attached to the twig, which dies from the 
point of infection outward, and with its dead leaves shows 
very prominently in the green foliage of the tree as though 
it had been broken and remained hanging. At the point 



Diseases and their Control 383 

of infection a few drops of gum usually form. During rainy 
weather the sclerotia (small black bodies a little larger than a 
grain of wheat) will often be formed on the outside of the 
bark near the point of infection. Sclerotia rarely form in 
hot, dry weather. Apparently, infection can only occur by 
spores finding lodgment in abrasions of the bark. While 
the spores of this fungus are very plentiful in southern 
California, often causing serious losses in the packing-houses, 
yet for reasons not at present understood, blighting of the 
twigs is so rare as to cause but little damage. While the 
casual observer may notice a blighted twig here and there in 
almost any orchard either of oranges or lemons, it has never 
been reported as doing sufficient damage to the trees to 
warrant remedial measures. This trouble is very often 
mistaken for wither-tip. As a matter of course all blighted 
branches should be removed when the trees are pruned. 

This fungus has also been found on the bark and roots of 
old trees. The bark is decayed and, when dried out, comes 
away in fibrous shreds very characteristic of this fungus. 
Remedial measures for this form of the disease have not been 
worked out. Meanwhile the treatment advised is to cut 
away all diseased tissue and paint the wound thoroughly 
with bordeaux paste. 

Cottony mold (Sclerotinia libertiniana) 

The same fungus described above develops not only on 
citrus twigs but upon the vetch used as a cover-crop and on 
orchard soils. The sclerotia which form on the twigs and 
on the vetch finally dry and fall to the ground. The following 
rainy season, after being thoroughly moistened they give 
rise to small funnel-shaped toadstool-like bodies which produce 
the spores of the fungus in great quantities. These spores 
apparently require an abrasion in order to germinate and 



384 



Citrus Fruits 



grow in the fruit. Once the fungus has begun growth in 
a lemon its progress is rapid. A large amount of white 




Fig. 134. — A " nest" of cottony fungus. 



cotton-like mycelium is produced in which the characteristic 
black sclerotia are formed. An important point to bear in 



Diseases and their Control 385 

mind is the fact that while the spores of the fungus require 
an abrasion for inoculation, the white mycelium is abun- 
dantly able to grow into and infect a perfectly sound lemon 
at any point. The decay is often very serious in stored 
lemons, the fungus spreading rapidly in all directions from 
the lemon originally infected. Unless discovered and re- 
moved in time cottony mold often destroys an entire half- 
box or even a whole stack of stored lemons. For this 
reason packing-house men are always on the watch for 
"nests" of the cottony fungus, carefully removing the 
source of infection as soon as discovered, and disinfect- 
ing the contaminated boxes with very strong bluestone 
solution. 

The disinfecting solution used in the wash-water against 
brown rot does not kill the thicker walled spores of this 
fungus ; in fact, bluestone solution of sufficient strength to 
kill the spores would produce serious spotting of the lemons. 
Preventive measures must therefore be taken in the orchard 
when the lemons are picked. It is suggested that the lug- 
boxes be placed on bare ground or at least not left standing 
for days in the vetch where the spores of the fungus are pro- 
duced. Empty boxes so placed may easily become dusted 
with spores, and inasmuch as it is the custom in many houses 
to submerge the full lug-boxes in the wash-water as the 
lemons are gently emptied, the spores are readily transferred 
to the water. The cut surface of the stem of the lemon where 
it was severed from the tree affords ample opportunity for 
spore infection in the washing-tank. 

Cottony mold is most severe on lemons and occurs sporadi- 
cally, being worse in certain sections and in certain years. 
It may be wise to temporarily discontinue the use of vetch 
as a cover-crop in orchards where cottony mold has become 
well established. 

2c 



386 . Citrus Fruits 



Brown rot fruit decay (Pythiacystis citropkthora) 

It has been shown that this fungus causes gum-disease of 
the tree. It also causes a serious decay of the fruit. The 
fungus lives normally in the soil even at considerable depths. 
It comes to the surface during wet weather in winter and 
produces spores on the surface of the ground, especially 
in damp, shady places, such as under citrus trees. The 
spores are motile and can swim around in a thin film of water. 
The drip from the tree splashes these spores upon fruit hang- 
ing within two or three feet of the ground. The spores 
enter the stomata or breathing pores, germinate, and grow 
within the fruit, producing a soft, watery decay which has a 
peculiar brown color and a characteristic odor. All citrus 
fruits are affected, but lemons are especially susceptible. 
During wet winters, the losses from this cause are often very 
great. The decay spreads rapidly in the packing-house as 
the mycelium is able to infect perfectly sound fruit by con- 
tact. If not discovered and removed, the decay starting 
from one lemon may run through an entire box or a stack of 
boxes in storage, and, in a short time, reduce the whole to 
a watery mass. 

Fortunately a simple and very effective remedy is now in 
use in all packing-houses. The spores of the fungus being 
very thin walled are extremely susceptible to copper sulfate, 
and in order to free any packing-house of this pest it is only 
necessary to add bluestone to the wash-water. The common 
practice is to add 1| pounds of bluestone to each 1000 gallons 
of water in the morning and then fortify this with an addi- 
tional pound at noon after considerable fresh water has 
entered the tank. As bluestone attacks metal, wooden or 
cement tanks should be used. Some prefer metal tanks 
coated with asphaltum. Should the wash-water contain 



Diseases and their Control 387 

alkali the bluestone may be neutralized, and in such cases a 
chemist should be employed to study the water and advise 
as to the proper procedure to keep the solution of bluestone 
as near as possible at a strength of -^ of one per cent. 

In order to reduce to a minimum the loss of lemons on the 
trees it is advisable to keep the branches pruned up some- 
what from the ground, and summer cultivation should extend 
well under the trees. It has been found well worth while 
also to spray the ground under the trees each fall before 
the rains begin with bordeaux mixture, as this largely pre- 
vents the fungus from fruiting at the surface of the ground. 

Blue mold (Penicillium italicum) and green mold 
(P. digitatum) 

Most of the decay of citrus fruit is due to blue and green 
molds. Being only very slightly parasitic on uninjured fruit, 
the decay is practically confined, under ordinal conditions, 
to fruit which has been injured in handling. The spores of 
these fungi are very common in the air everywhere and 
are almost sure to get into any slight abrasion of the skin 
of fruit. They produce a soft rot while the fungi fruit 
abundantly over the surface, the spores appearing as a blue 
or a greenish powder according to which species is present. 
Frequently the two kinds occur together, although the green 
is the most universal. For all practical purposes these two 
species of penicillium may be treated as one. About the 
only difference is the color of the spores and the fact that in 
pure culture the blue mold shows a wider band of white 
exposed mycelium between the fruiting area and the sound 
skin. The universal preventive for these decays is careful 
handling of the fruit in field and packing-house, which, 
if conscientiously enforced, will reduce the losses to a 
minimum. 



388 



Citrus Fruits 



Gray mold (Botrytis vulgaris) 

Occasionally lemons while in storage will develop what is 
known as gray mold. It appears as a dark brown discolora- 
tion and softening which is followed by the mycelium which 
appears at the surface and produces gray or mouse- 
colored spores. The fungus is apparently dependent on 
abrasions for access to the fruit and would no doubt be 
much more abundant were it not for the fact that the blue 
and green molds usually monopolize such opportunities for 
development. 



Black, rot of Navel orange (Alternaria citri) 

Navel oranges only are subject to black rot which may be 

recognized by the 
premature ripening, 
abnormally large 
size, and very deep 
red color. The 
affected fruits are 
very conspicuous on 
the trees before the 
main crop has col- 
ored up. The 
spores of the fungus 
gain entrance at the 
navel end through 
slight imperfections 
of the peel or per- 
haps through the 
stigma of the blos- 
som, and produce a black, decayed area under the skin. 
This decay does not immediately spread through the entire 




Fig. 135. — Black rot of Navel. 



Diseases and their Control 389 

fruit, but remains for weeks as a small black mass of fungus. 
Decayed tissue may occasionally extend to the surface, but 
more often this is not the case and the fruit finds its way 
into the hands of the consumer. 

There is no known remedy for this trouble which occa- 
sionally affects as much as one per cent of the crop in certain 
localities. It is suggested, however, that all affected fruits 
should be gathered up and burned in order to reduce the num- 
ber of spores in the orchards. 

Brown spot of Navel orange 

The brown spot of the Navel orange may be described as 
occurring irregularly over the surface of the orange. From 
one to fifty or more spots may develop on a single fruit. The 
spots vary in size from a mere point to one inch in diameter, 
averaging about one-fourth inch. In outline they seem to 
follow no rule and may be quite irregular, although the cir- 
cular spot is most common. The color of the spot varies in 
different localities from a pale brown, which attracts little 
notice, to almost black, in which case the good appearance 
of the fruit is ruined. The eating qualities of spotted oranges 
are not injured in the least. The color of the spot seems to 
be lighter near the coast and darker in the interior valleys. 
Losses from brown spot have been heaviest from the upper 
San Gabriel and Santa Ana valleys, because in these regions 
the spotting is more common and the color changes to a darker 
brown. On the other hand, the fruit from many of the pack- 
ing-houses near the coast shows brown spots of such a pale 
tint as to attract no notice on the market. The spots are 
darker on early picked fruit, and it seems to be true that if 
the fruit is left on the trees until very late it will not spot at 
all. The spots are slightly sunken on account of the fact 
that the surface cells have collapsed. The dead and col- 



390 



Citrus Fru its 



lapsed tissue extends from the surface to about one-fourth 
the thickness of the rind. No spots are visible while the fruit 
is on the trees and as a rule the spots are not noticeable till 
from 15 to 25 days after picking. On this account it is not 
possible to grade against this spot in the packing-houses, 
unless storage houses of sufficient capacity are built to hold 

the pickings of three 
or four weeks. 

The brown spot has 
been observed so far 
chiefly on the Wash- 
ington Navel orange, 
and dealers have com- 
plained of it only on 
this variety. In 1914 
the writer received 
specimens of Valencia 
oranges from Highland 
which had been picked 
about the first of June 
which showed almost 
typical brown spot. 
The color was lighter and less damaging than usually occurs 
on the Navel. Spotting is uniformly worse on fancy, 
smooth, thin-skinned fruit. The fruit which grades highest 
as it comes from the orchard always spots much more than 
the rough fruit, which often remains exempt. Examination 
of the spots with a hand lens fails to show any abrasion or 
opening in the epidermis. 

Orange packers have been complaining of the brown spot for 
only four or five years, but it is probable that it has existed, 
though varying in severity, as long as the Navel orange has 
been cultivated in California. 




Fig. 136. — Brown spot of Navel orange. 



Diseases and their Control 391 

Up to the present time neither the primary cause nor a 
remedy has been discovered. After an extended investiga- 
tion the writer was led to conclude l " That the direct cause of 
brown spot is the oxidation of the protoplasm by enzymes 
which occur in the protoplasm itself but which are prevented 
from acting as long as the orange is joined to the tree and 
receiving water and certain nutritive substances from the 
tree. Thus the resistance of the protoplasm to enzyme en- 
croachments gradually grows less from the time the orange 
is picked." This conclusion merely takes the real question 
one step farther back, for the practical citrus men will, of 
course, wish to know the primary causes which bring about 
such premature death. This question cannot be answered at 
the present time. 

Damping-off (Rliizoctonia sp. and Fusarium sp.) 

Citrus seed-beds are often seriously injured by damp-off 
fungi. The very young plants begin to die in spots which, 
rapidly extending, involve large areas if not checked. Two 
forms of the disease are recognizable, one caused by the 
Rhizoctonia which kills the stem just above the ground, while 
the other shows itself in dead spots on the stem at any point. 

These troubles should be prevented by strict attention to 
proper methods of planting and watering. No manure or 
freshly decaying organic matter should be applied to the 
seed-bed, commercial fertilizers being used exclusively. The 
seed should be covered with a layer of clean, fresh sand which 
will prevent the surface from becoming too wet. For the 
inexperienced grower, particularly, it is better to make wide 
furrows, two inches deep, about a foot apart, planting the 
seed broadcast on the ridges between. The water may then 

1 "The Brown Spot of the Navel Orange," Proc. Soc. for 
Hort. Sci., 1900. 



392 Citrus Fruits 

be run in these furrows and allowed to soak into the ground 
laterally, thus keeping the surface of the sand dry. Where 
the seed is sown broadcast over the whole surface of the bed 
and the water applied by sprinkling, watering should always 
be done on sunny mornings and no oftener than is absolutely 
necessary. In most cases a good watering once a week is 
sufficient to keep the soil under the sand sufficiently moist. 
Should the seedlings begin to damp off in spite of all precau- 
tions, it is advisable to allow the bed to go as dry as is reason- 
ably safe, and then spray the surface of the bed with a rather 
weak bordeaux mixture, being careful to wet the entire surface 
of the soil. 

Citrus Canker 

Very recently a new disease has appeared in the Gulf States 
which is described as the most serious which affects the 
pomelo. Sweet oranges are apparently immune. It exists 
in Florida and Alabama, the first specimens being collected 
in 1912. So far it has not been reported from California. 
H. E. Stevens describes the trouble as follows : * " The 
disease appears as small, circular spots, from less than one- 
sixteenth to one-quarter of an inch across. They may occur 
singly, or several together may form an irregular area. They 
are raised above the surrounding tissue, are light brown, and 
composed of a spongy mass of dead cells covered by a thin 
(white to grayish) membrane that finally ruptures and turns 
outward, forming a ragged margin around the spot. The 
general appearance of the spots is much the same whether 
they are found on the leaves, fruit, or twigs. The older 
spots often become overgrown with saprophytic fungi, and 
may be pink or black on account of secondary infection by 
species of Fusarium or Cladosporium. 

1 "Citrus Canker." H. E. Stevens, Florida Exp. Sta. Bull. 
No. 122, 1914. 



Diseases and their Control 393 

"The infections on the leaves appear first as small watery 
bulging dots, which are usually of a darker green than the 
surrounding tissue. They may appear on either surface 
of the leaf, but do not penetrate through the leaf tissue at 
this stage. The spots gradually increase in size, change to 
a light brown color, and become visible on both sides of the 
leaf. The spot may project from the surface on one or both 
sides of the leaf. Each spot is surrounded by a narrow yel- 
lowish band or zone. Later the surface of the spot becomes 
white to grayish, and finally ruptures, exposing a light-brown 
spongy central mass. 

"The spots on the fruit are similar to those on the leaves. 
They project from the surface and retain a circular outline. 
They do not penetrate far into the rind, and may be scattered 
singly over the surface, or several may occur together, forming 
irregular masses. 

"The spots on the older twigs are more prominent and 
usually larger and more irregular in shape. They show the 
same spongy tissue and the same color as those on the leaves. 
On growth more than a year old, the spots assume a cankerous 
appearance and the membrane covering the surface disap- 
pears. The spots do not penetrate to the wood, but are con- 
fined to the outer tissues of the bark. 

"The organism causing the disease has not been deter- 
mined, but it is probably a fungus. Several different fungi 
have been found associated with the spots, among which a 
species of Phyllosticta 1 occurs most frequently. This fungus 
is suspected of being the cause of the trouble, and experi- 
ments are now in progress to determine this. 

"The disease is infectious, as is shown by the results of 
some experiments in which it was transferred from diseased 
material to healthy leaves and shoots of grapefruit." 

1 Later found to be a species of Phoma. See Wolf and Massey, 
Circular 27, Alabama Experiment Station. 



394 Citrus Fruits 

Control measures have not yet been fully worked out. 
On account of the presence of this fungus, the state of Florida 
is now quarantined against the introduction of nursery stock 
or bud-wood from Alabama. 

Melanose and Stem End Rot (Phomopsis citri) 

These diseases, which are both caused by the same fungus, 
have been prevalent in Florida for many years. The fungus 
occurs in Australia, Jamaica, Porto Rico, and Algeria, but so 
far has not been found to exist in California. 

The disease lives normally and produces spores on dead 
twigs in citrus trees. The spores are washed by the rains 
over the surface of the fruit, causing, particularly on pomelos, 
peculiar brownish streaks known as tear-staining or melanose. 
These marks are nearly the same on leaves, stems, and fruit, 
and consist of raised areas of brown gum-filled cells forming 
dots, lines, rings, or irregular spots which greatly injure the 
general appearance of the fruit while not injuring the eating 
quality. 

Stem-end rot causes the fruit to drop, beginning with im- 
mature fruit in August and continuing till after the fruit has 
been sent to market. It even causes decay after the fruit 
has reached market. The softening begins at the stem 
end and is especially common on fruits which have scale 
insects about the stem end. . It is more severe during a warm 
fall and winter, and infection seems to be more common in 
damp shady situations. Sound picked fruit can be infected 
by contact with diseased fruit. The fungus inhabits the 
soil under infected trees and the spores develop in spring 
and summer on dead twigs, bark, and on mummified fruits. 

The application of fungicides to the trees or disinfectants 
to the wash-water does not control the disease. The most 
successful method of control is to keep the trees carefully 



Diseases and their Control 395 

pruned and free from all dead twigs, stubs, and mummified 
fruits. The primings should not be plowed into the soil, but 
should be removed from the orchard and burned before the 
fungus has time to grow and produce spores upon this ma- 
terial. All diseased fruit which falls to the ground should be 
collected and destroyed. Careful culling at the packing- 
house and refrigeration in transit are aids to control. Also 
it is advisable to keep the trees as free as possible from 
scale insects. -* 

Nail-head Rust (Cladosporium herbarum var. citricolum) 

In Florida the nail-head rust is quite common, while it has 
not as yet been found in California. It is often called scaly- 
bark in Florida, but it is very distinct from the California 
scaly-bark, the cause of which has not yet been discovered. 
The disease appears on the twigs and small branches as 
slightly raised rusty spots, as implied by the name. The 
fungus also produces spots on the fruits which are hard, cir- 
cular, sunken, and more or less corky. Affected fruits color 
and drop prematurely. The spots due to this fungus are 
found only on sweet oranges. Various control measures 
have been suggested, such as top-working the trees to pome- 
los ; heading back and spraying with bordeaux, followed by 
an insecticide ; and carefully pruning out all dead wood. 

Scab or Verrucosis (Cladosporium citri) 

Citrus scab is another disease which occurs in Florida and 
other parts of the world but has not so far been found in 
California. The following description of scab is from the 
Florida Experiment Station Bulletin No. 108, page 41. 

" This disease, which is especially common on sour oranges 
and lemons, makes its appearance on the fruit as irregular 



396 Citrus Fruits 

light brown or corky projections from the surface. It is 
caused by a fungus which attacks the fruit or leaves when 
quite young. Its attack on sour oranges and lemons (and 
sometimes on Satsumas and grapefruit) often results in 
making them misshapen and unsightly. In severe attacks, 
projections of a dark gray to corky or even tan color will be 
seen extending out from the surface. The surface of the 
fruit between the warts is usually of a normal color. Often 
these irregular corky projections coalesce to form a large 
raised corky scab. In less severe attacks, especially when 
scab occurs on grapefruit and on tangerines (or rarely on 
sweet oranges), the warty irregular projections are wanting, 
and there will be seen more or less raised platform-like 
patches variable in shape and extent. The surface of the 
raised portion is finely scabbed or lightly scurfed, as is seen 
in the case of thrips marks or silver scurf. In this milder 
form it can usually be distinguished from thrips marks or 
other forms of scurf by its being raised, but can be distin- 
guished with certainty only by the use of the compound 
microscope. 

" The scab can be completely controlled by the use of weak 
bordeaux mixture (3-3-50). Since (in Florida) the use of 
bordeaux on orange trees, however, kills the friendly fungi 1 
and allows a rapid increase of scale insects or white-fly, this 

1 It should be explained for the benefit of those not familiar 
with conditions in Florida that there are a number of kinds of 
fungi which prey as parasites upon the scale insects and white-fly 
larvae and are thus of very great benefit to the citrus growers. 
Some of these friendly fungi occur in India and other places, 
but so far none have been successfully established in California, 
where the air is too dry perhaps for their success. In spraying 
with bordeaux for fungus diseases in Florida, the killing off of 
these friendly fungi has to be considered, for an application of 
bordeaux usually must be followed by an insecticide on account 
of the great sudden increase of scale insects. 



Diseases and their Control 397 

spray is not recommended except when it is absolutely neces- 
sary. When it must be resorted to, a good insecticide should 
be used as soon as the scale insects begin to increase rapidly. 
Some of the harm from increase of scale insects may be pre- 
vented by spraying the bordeaux as much as possible only 
on the fruit, and keeping the spray off of the larger limbs and 
the inside of the tree where the friendly fungi may be left 
alive." 

Dijjlodia Rot of Oranges (Dijjlodia natalensis) 

A form of fruit decay which occurs in Florida and South 
Africa but has not so far been reported from California. 
H. S. Fawcett gives the following description of it in Florida 
Exp. Sta. Bull. 108, p. 46 : 

"In the early stage this rot shows as a patch about the stem 
end similar to stem-end rot. The discoloration becomes 
darker as the decay proceeds, and appears as dark wide bands 
corresponding to the divisions between the segments. The 
fruit becomes black as the decay advances and very light in 
weight. The rot often advances quickly through to the 
'blossom' end, and a patch of discoloration shows there 
before all the peel is involved. The Diplodia rot often 
starts also in thorn punctures or similar injuries. It is 
usually accompanied by the exudation of a small amount of 
thin gum, or a considerable amount of amber-colored sticky 
juice. This amber-colored juice less frequently accompanies 
the stem-end rot. Many of the characteristics of the two 
rots are so similar that for practical purposes they may be 
classed together. The citrus fruits are much more resistant 
to Diplodia rot than to stem-end rot. Diplodia rot appears 
to be less common on immature fruits on the tree, and the 
fungus causing it is less parasitic. The same methods of 
treatment given for stem-end rot hold good for the Diplodia 
rot." 



398 Citrus Fruits 

Red Blotch of Lemon 

It is in stored fruit alone that red blotch develops. It is 
often called "red rot" by packing-house men but as it is 
apparently not due to any parasitic organism the latter name 
is misleading. It is characterized by the rind shrinking and 
turning to a dark color in large spots or blotches. The 
discoloration is usually limited to one side of the fruit and 
gradually changes from rusty bronze to dark red and finally 
to black. On cross section, affected fruit shows the discolora- 
tion about the seeds, the central core, and along the parti- 
tions, while the vesicles appear normal. The disease does 
not spread among the lemons by contact. It is unusual 
for red blotch to develop in large amount in any one house, 
although the losses in the aggregate are large. It has been 
suggested that red blotch may be caused by sunburn or 
overheating of the lemons on the tree, but so far neither the 
true cause nor a remedy has been demonstrated. 

Yellow Spotting of Oranges 

In all the interior valleys of southern and central California 
and in Arizona it. is the usual thing for oranges of all varieties 
to develop small bright yellow spots before the oranges are 
mature. Often these spots are very conspicuous on account 
of the contrast with the green rind. Usually all the oranges 
on the exterior of the trees and especially those near the 
ground show the spots. When the fruit colors naturally 
there is no longer any contrast and the spots are no longer 
visible to any but an experienced eye. As these spots do not 
damage the fruit for eating or for sale but little interest 
has been shown in determining the cause. They are probably 
due to the bites of some small insect such as a leaf -hopper, 
many species of which are common in the orchards. At 



Diseases and their Control 



399 



one time it was thought that these spots later developed into 
the brown spot of the Navel orange, but this has been shown 
not to be the case. 

Stem End Spot 

The California stem end spot of oranges is a very different 
thing from the stem end rot common in Florida and pre- 
viously described. It 

appears as small dried 
out and sunken spots 
immediately adjacent 
to the stem of the 
fruit and is most seri- 
ous on the Navel 
orange. It occurs 
only on fruit which is 
beginning to age. The 
cause has not been 
clearly demonstrated. 
Sometimes during wet 
weather, saprophytic 
fungi may grow on 
these dead spots, in Fig. 137. — Stem end spot of orange. 

which case the appear- 
ance of the fruit is injured and it is not safe to ship it to 
market. The remedy is to pick and ship the fruit earlier. 




Trunk Rot (Schizopyllum commune) 

The decay of the trunks of citrus trees due to this fungus is 
especially common in the moist coast region and in northern 
California. Where stubs have been left in careless pruning of 
the large limbs the spores gain entrance, and in time the white 
bracket-like fruiting bodies appear. The fungus is thought 



400 



Citrus Fruits 



not to be strongly parasitic on sound healthy tissue, but once 
started it may cause dying back of the wood. The disease 
may easily be prevented by paying proper attention to the 




Fig. 138. — Pruning stub on orange tree affected with Schizopyllum. 



disinfection of pruning wounds and by covering all large 
cuts with a suitable dressing. Inasmuch as the presence of 
this fungus indicates neglect, it reflects discredit upon the 
orchardist. 

There are several other kinds of fungi which have not been 
identified which, after getting started in sunburn cracks or 



Diseases and their Control 401 

frost injuries, may cause a progressive decay of the wood 
of citrus trees. All these may be prevented by care and 
attention to injuries. When once well started it may require 
rather extensive tree-surgery to entirely rid the tree of the 
infection. 

Galls and Knots 

Occasionally large galls are found on the branches of citrus 
trees in California. They are not common or very injurious, 
and the only remedy suggested is to prune them out. These 
galls may be due to the crown gall organism which produces 
similar galls on the roots of peach, almond, and other fruit 
trees. Crown gall has been produced on citrus trees experi- 
mentally by C. O. Smith of the University of California. 

Recently Florence Hedges x investigated a rather serious 
and contagious form of gall on citrus trees from the Island of 
Jamaica. The cause was discovered to be a fungus, Sphcerop- 
sis tumefaciens. All the galls so far found in California 
have been different and the contagious Sphozropsis gall is not 
known to occur either in California or Florida, although 
common in Cuba. 

Black Pit of Lemon (Bacterium citriputeale) 

A serious blemish which occurs occasionally on tree-ripe 
lemons late in the spring. This trouble is apparently con- 
fined to southern California. It appears as large dark red 
or black spots, the surface of which is firm and markedly 
depressed below the general surface of the rind. The spots 
do not increase in size rapidly or progress into a general 
decay, but the appearance of the fruit is ruined. The cause 

1 "A Knot of Citrus Trees Caused by Sphceropsis tumefaciens " 
by Florence Hedges and L. S. Tenny, U. S. D. A. Bureau Plant 
Industry, Bull. No. 247, 1912. 
2d 



402 Citrus Fruits 

is a bacterium which gains access to the rind through thorn 
punctures. Apparently an abrasion is necessary before the 
bacteria can enter. The trouble may be prevented in three 
ways : pick the fruit before it becomes tree-ripe, grow 
thornless varieties, or protect the orchard by windbreaks. 



CHAPTER XXII 
CITRUS INSECTS AND THEIR CONTROL 

The number of insects which seriously attack citrus 
fruit trees in California is not large ; their lack in numbers, 
however, is more than offset by their aggressiveness and 
their ability to withstand control measures. While it is 
true that fumigation for scale and spraying for red spider 
or mites, if properly done, is supposed to kill all the in- 
dividuals on the trees at the time of treatment, yet in actual 
practice a few usually survive and later reinfest the trees, 
so that in the course of time remedial measures must be 
repeated . 

The financial loss due to the various citrus pests is large, 
the cost of control amounting to more than half a million 
dollars a year in southern California, according to a re- 
cent estimate. This does not take into account the 
secondary losses due to weakened trees, dirty fruit, and 
fruit scarred by thrips or mites. The state as well as the 
nation is spending large sums annually in studying citrus 
pests and in devising better methods of control, while in 
addition to this most counties employ a horticultural com- 
missioner and a corps of inspectors whose chief duty is to 
assist in controlling pests already established in the county 
and to prevent the introduction of foreign species. 

403 



404 Citrus Fruits 

The distribution of the various citrus insects in Califor- 
nia is greatly influenced by the different climatic conditions 
obtaining in the different parts of the state. The purple 
scale has so far not become established nor is the black 
scale serious on citrus trees in the hot dry air of the interior 
valleys. The red and yellow scales are both found in the 
San Joaquin citrus districts, although not in injurious num- 
bers, while the yellow scale alone is found in the Sacra- 
mento districts. Before the introduction of various in- 
sect pests into California from Florida, the general opinion 
prevailed that such insects would not thrive when taken 
from a humid into a comparatively arid climate. The 
fact that any particular insect has not so far become es- 
tablished in a given region must not be taken as sufficient 
evidence that it will not thrive when an opportunity to 
infest trees presents itself. 

At the present time, it is very encouraging to note the 
fact that in the better kept citrus orchards of the state 
it is often difficult to find specimens of certain insects for 
study. In some localities where red and yellow scale, 
mealy bug, or silver mite were once very abundant, it may 
now require a diligent search to locate a single individual, 
so effective has been the work of the inspectors and the 
application of remedial measures. 

A point which should be emphasized is the importance of 
keeping orchards and fence rows free from weeds which 
harbor scale. One of the worst offenders among weeds 
is the common nightshade (Solatium nigrum) which is so 
abundant throughout most of the state. Even after 
thorough fumigation of the trees has been accomplished, 
a few scales living on the nightshade will start a new infes- 



Citrus Insects and their Control 405 

tation, the blame for which is often unjustly charged to 
carelessness of the fumigators. 

For sake of convenience, insects are usually divided into 
two general groups, the biting insects and the sucking in- 
sects. The biting insects are those which bite or tear off 
pieces of the plant tissue and actually consume parts of 
leaves or the tissues upon which they are feeding. The 
sucking insect on the other hand pierces the tender plant 
with a slender proboscis or tube-like mouth-part and 
proceeds to extract the sap from the cells. All the scale 
insects, the mealy bugs, the plant lice, and the red spider 
have sucking mouth-parts, the thrips have mouth-parts 
fitted for both rasping and sucking, while the rose 
beetle, the orange tortrix, and the diabrotica are biting 
insects. 

A proper understanding of the manner in which an in- 
sect obtains its food is necessary before remedial measures 
can be intelligently applied. For biting insects, a stomach 
poison such as paris green or arsenate of lead should be 
used, while for sucking insects, a solution or gas which kills 
by contact,' such as lime-sulphur or kerosene emulsion or 
hydrocyanic acid gas, is necessary. A contact insecticide 
either fills up the breathing pores which are located along 
the sides of the body of the insect, thus suffocating them, or 
produces fatal irritation. The sucking insects are by far 
the most destructive and troublesome in citrus orchards 
as well as the most difficult to control. 

Black Scale (Saissetia olea?) 

The black scale is widely distributed over the earth, since 
like other scale insects, it is very easily carried from one 



406 



Citrus Fruits 



country to another on young nursery trees and ornamental 
plants. This scale is perhaps the most damaging insect 




Fig. 139. — Black scales on orange twig. 

pest of the citrus districts in the Mediterranean region. The 
exact date of its introduction into California is not known. 



Citrus Insects and their Control 407 

According to a report published in 1880, it was well es- 
tablished at that time. It is found in nearly all the counties 
of the state, although as a citrus pest it is troublesome chiefly 
in southern California, especially near the coast. In Los 
Angeles, Santa Barbara, and Orange counties it takes first 
rank among citrus insects, while in Ventura and San Diego 
counties it is given second rank. In Western Riverside 
and San Bernardino counties, it is also a serious pest, as is 
shown by the fact that 75 per cent of the insect control work 
in Riverside county in 1910 was directed against the black 
scale, although such a high percentage is unusual. 

The black scale injures the tree by sucking the sap. The 
greatest injury, however, is done indirectly by the sooty mold 
which accompanies the scale. The insect excretes copious 
amounts of a substance, known as honey-dew, which falls 
upon the leaves and fruit below. This furnishes a suitable 
medium for the growth of the sooty mold fungus (Mcliola 
camellia) which not only clogs up the breathing pores of 
the leaves and renders them incapable of performing their 
normal functions, but. also forms a black coating over the 
fruit which necessitates thorough washing before the fruit 
can be packed for market. This washing is often of neces- 
sity so severe as to cause abrasions in the skin and a con- 
siderable increase in the amount of decay during transit 
to market. 

The size of the adult scale will average about one-seventh 
of an inch in length and not quite as broad. It may be dis- 
tinguished from closely related species by a plainly outlined 
letter H on the back of the full grown females. The color 
of the mature female is usually very dark, often jet black. 
The male scale is minute and is very seldom seen. When 
mature the male emerges from its pupal case as a winged 
insect. 



408 Citrus Fruits 

The life history of the black scale varies in different sections, 
but in general it is about as follows : 

Eggs are produced most abundantly in May, June, and part 
of July, the average number found under each scale being 
about eighteen hundred. In about twenty days the eggs 
hatch. At the end of a day or two the young insects make 
their way out from under the protecting mother scale, and 
crawl around for two or three days before settling down, 
the leaves and tender twigs offering the most suitable feeding 
ground. Unlike the armored scales, the black scale is, up 
to a certain age, able to withdraw its sucking mouth-parts 
from the tissues and move to more favorable pasturage. 
This accounts for the fact that only a few mature individuals 
are seen on the leaves, while such large numbers are found 
on the branches. 

The yellowish half grown females are most common from 
about the middle of September to the middle of December, 
while during the spring and early summer months the dark 
adult scales are most abundant. Although there seems to be 
but one generation of the black scale during the year, it is not 
uncommon along the coast to find all stages at one time. 
It is this irregularity in the appearance of the young scales 
that makes the problem of control so difficult. The insect 
is naturally most susceptible to any destructive influence 
during the two or three days when it is crawling around 
searching for a suitable place to feed. The hot dry air of 
the interior valleys kills them off in large numbers and they 
are not able to establish themselves so readily as in the coast 
sections. 

The young insects may readily be seen crawling about over 
the leaves and stems, but a little observation will show that 
their powers of locomotion are very limited ; they are not 
able to crawl from one tree to another over the rough ground 



Citrus Insects and their Control 409 

and must depend upon some other agency to carry them 
any considerable distance. Probably the most common 
agents for their dispersal are the ladybird beetles. These 
and other insects are often found with one or more young 
scales on their backs, and when the beetles fly to other trees, 
the scales are carried along to start new infestations. Birds 
are probably responsible for transporting young scale 
insects long distances, as the latter have ample opportunity 
to crawl upon the bodies of birds which are roosting in the 
trees or resting between flights. Man, however, has been 
mostly responsible for the wide distribution of the black 
and similar scales, especially by the shipment of promiscuous 
lots of nursery stock from one country, or one section to 
another. In the orchard the young scale is very liable to be 
distributed during the ordinary operations of cultivation, prun- 
ing, picking, and hauling to market. In some packing-houses 
the precaution is taken of fumigating all lug-boxes as they 
are emptied. They are loaded directly into the wagons 
from the fumigating room, to be taken back to the orchard: 
In this way the danger of introducing scale into a clean or- 
chard by means of lug-boxes is reduced to a minimum. 

There are several natural enemies of the black scale in 
California. Among these, the most important is the parasite, 
Scutellista cyanea, which was introduced from South Africa 
in 1900 and is now found in most of the districts where black 
scale abounds. The Scutellista is an egg parasite and the 
larvae feed only on the eggs which are deposited by the mature 
black scale. In some cases all the eggs under one scale 
may be consumed, but in other cases the parasites come to 
maturity with a greater or less number of eggs untouched. 
Even if the eggs are completely destroyed in the parasitized 
scales, there are usually a sufficient number of female scales 
which are not parasitized to carry on the infestation. While 



410 Citrus Fruits 

the Scutellista aids materially in reducing the numbers of 
the scales, it cannot be depended on alone for the effective 
control of the pest. 

Another egg parasite, Tomocera califomica, is found in 
some sections but is not nearly so effective as the preceding. 
There are at least four ladybird beetles as well as an internal 
parasite of the male insect which also prey upon the black scale. 

Where only a few trees around the house are infested or 
only young trees require treatment, spraying with distillate 
emulsion or kerosene emulsion is recommended. The emul- 
sion is made as follows : 

Kerosene 1 gallon 

Soap (laundry) § pound 

Water 15 gallons 

The soap should first be dissolved in about a gallon of hot 
water, and while still hot, add the kerosene, away from the 
fire. The mixture may then be emulsified by churning it back 
and forth for several minutes until it becomes of, the consist- 
ency of cream, when it is diluted to make the sixteen gallons. 
The oil should be thoroughly emulsified before being used, 
as free oil in the mixture is apt to cause serious injury to 
the bark of young trees. Where the soil is sandy the con- 
centration of the spray material which runs down the 
trunks and reaches the soil may cause injury at the collar. 
In such cases the oil-saturated soil should be removed 
from about the collar and replaced by a few handfuls of 
fresh soil. This should be done three or four hours after 
the spray has been applied. 

Fumigation is usually more effective, however, in control- 
ling black scale, as the gas penetrates to all parts of the tree 
and the fumigation properly done kills both the mature and 
half grown scales. 



Citrus Insects and their Control 



411 



The Red or Orange Scale (Chrysomphalus aurantii) 

The red scale is found along with the black scale in the 
southern coast counties, where it is a serious enemy of citrus 




Fig. 140. — The red scale on orange. 

trees. It takes first rank as a pest in San Bernardino and 
Riverside counties, while in Orange and Los Angeles counties 
it takes second place. It was found in California in 1878, 
and the origin of that infestation was traced to Australia, al- 



412 Citrus Fruits 

though China is usually regarded as its native home. It 
occurs in nearly all tropical and semi-tropical countries on a 
large number of plants, but is especially a pest on citrus 
trees. Unlike the black scale, it does not produce honey- 
dew. The injury to the tree is due either to the loss of sap 
or to the poisonous effects upon the cells of the tissues 
attacked. While the black scale is never known to kill 
a tree upon which it is feeding, the red scale quite commonly 
affects its host plant very seriously if not fatally. It also 
settles upon the fruit, marring its appearance and market 
qualities. The life history differs from that of the black 
scale in the fact that the mature female does not produce 
eggs but gives birth to living young. These young scales 
are minute, but may be observed from June to September or 
later as yellowish mites crawling on the leaves, stems, or 
fruit. They do not migrate far from the parent scale unless 
the food supply is scarce or the feeding surface dry and hard, 
in which case they may travel several feet. The scaly cover- 
ing which the young insect begins to form over itself as soon 
as it is settled is simply for protection, and is not a part of 
the body, as in the case of the half grown black scale. It 
consists of a mass of light cottony threads secreted by the 
young scale ; later this is enlarged by the two cast-off skins 
of the growing larvse. Under this protection, they con- 
tinue to feed until mature, which requires from two and a half 
to three and a half months. The mature female scale is 
reddish in outward appearance and about the size of the 
head of an ordinary pin. The mature male scale is smaller 
and more elongated than the female. The male sheds its 
skin four times and emerges as a winged insect in from one 
and a half to two months. 

Although each female produces but from forty to eighty 
young, the fact that in southern California there are four 




Fig. 141. — Work of red scale on orange tree. 
413 



414 Citrus Fruits 

generations during the season accounts for their rapid in- 
crease. The same agents responsible for the spread of the 
black scale also disseminate the red scale. 

The internal parasites of the red scale do not seem to be at 
all effective in reducing their numbers, as only a small per- 
centage of the scales are parasitized. Several species of the 
ladybird beetles are commonly found attacking the red 
scale, but are not of much assistance in their control. Fumi- 
gation according to the schedule given in Chapter XXIII 
is the most effective remedy. 

Yellow Scale (Chrysomphalus aurantii var. citrinus) 

The yellow scale is but a variety of the red scale, and is 
identically the same in structure. It is somewhat yellow in 
color, although the color becomes much darker after the 
insect dies, when it is more difficult to distinguish from 
the red scale. The distribution is about the same as that of 
the red except in the Sacramento Valley, where the yellow 
scale seems to occur exclusively. 

The feeding habit of this scale differs from that of the red 
as its attacks are almost wholly restricted to the leaves and 
fruit. The seriousness of the injury is therefore much less 
and the health of the trees is not so seriously injured. 

The life history agrees with that of the red scale. There 
is an internal parasite which sometimes kills 25 per cent of 
the scale, but fumigation must be relied upon for its com- 
plete control. 

The Purple Scale (Lepidosaphes beckii) 

The date of introduction of the purple scale into California 
seems to have been either 1888 or 1889, when two carloads 
of orange trees were received from Florida and planted in 



Citms Insects and their Control 415 

Los Angeles and San Diego counties without disinfection. 
It now occurs in San Diego, Los Angeles, Orange, Ventura, 
and Santa Barbara counties, and a strict inspection is being 
maintained in the more inland counties to prevent its intro- 
duction. The purple scale attacks all parts of the tree as well 
as the fruit, upon which they attach themselves so firmly 
that the ordinary washing is of little avail in removing them. 
They also cause the fruit to appear spotted in ripening, a 
green color persisting around the scales. Whole trees are sel- 
dom if ever killed by this scale, although the lower branches 
and often one whole side of the tree may be fatally affected. 

Eggs of the purple scale are most commonly found during 
the spring and early summer, although all stages may occur 
in the orchard at other seasons. The female produces 
from thirty to forty eggs, which hatch in about eighteen days 
during the summer months. The young remain under the 
protection of the mother for a short time, after which they 
make their way out and migrate in search of a place to feed. 
After they have once settled down and formed the protect- 
ing scale over their bodies the females are stationary dur- 
ing their entire existence. The mature female scales are 
elongated, and shaped somewhat like an oyster shell, the color 
varying from a dark brown to purplish. The male scale is 
much smaller and narrower. The average length of time 
from the egg to maturity is about two and one-half months 
for the male and three months for the female. After the 
production of eggs, the female soon dies. 

During the ordinary season, there are from three to four 
generations. The young seem to be more able to adapt them- 
selves to unfavorable feeding conditions than either the red 
or the black scales, and the percentage which become estab- 
lished is much greater. 

Several species of ladybird beetles prey upon the purple 



416 



Citrus Fruits 




Fig. 142. — The purple scale. (Enlarged.) 



scale, but only one internal parasite has so far been reared. 
This parasite is not very widely distributed and is only 



Citrus Insects and their Control ^Yl 

partially effective wherever it is found. In orchards where 
the red, black, and purple scales occur together, fumigation is 
mainly directed against the purple ; if it is killed, the dosage 
is usually fatal to the other two. 

Cottony Cushion Scale (Icerya purchasi) 

The account of the introduction, spread, and final control 
of the cottony cushion scale forms one of the most interesting 




Fig. 143. — The cottony cushion scale. (Enlarged.) 

chapters in the history of California horticulture. Having 
been introduced from Australia in 1868 (see Chapter I) 
it spread so rapidly during the next twenty years that its 
ravages proved a very serious menace to the citrus industry 
of the southern part of the state. The Australian ladybird 
beetle which was introduced into California from Australia 
in 1889 for the purpose of controlling this scale was so success- 
ful, to all appearances, that except for occasional outbreaks 
it ceased to be considered as a serious citrus pest, and fumi- 
gation or other measures of repression are no longer necessary. 
2e 



418 Citrus Fruits 

The mature scale is very easily distinguished from other 
scales. When mature, they are about one-fourth of an inch 
long and consist of the red or yellowish body and a large 
fluted cottony white mass which serves as the egg-sac. 
From five to eight hundred eggs are produced by each female, 
May and June being the season of greatest production. 
These hatch in about ten days in summer, but a longer period 
is required in winter. The young scales are very active, and 
feed at first largely upon leaves but later seem to prefer the 
twigs and branches. The females are able to move about 
during most of their life, but become stationary as soon as 
the egg-sac is formed. The time required for development 
from egg to adult varies considerably even during the same 
season ; the average, however, is about three and a half 
months. There are at least three generations in southern 
California, and during the summer months they increase 
very rapidly if not held in check by their natural enemies. 
The cottony cushion scale produces a large quantity of 
honey-dew, on which the sooty mold fungus grows readily. 

Soft Brown Scale (Coccus hesperidum) 

The soft brown scale is widely distributed over the earth 
and has a large number of food plants other than citrus. Its 
injury to citrus trees is due largely to the exudation of honey- 
dew, and the accompanying growth of the sooty mold fungus. 
It is only occasionally injurious, and seldom infests an entire 
orchard, being usually held in check by several internal 
parasites. This scale is usually accompanied by a great 
number of ants which feed upon the honey-dew. 

The young scales are produced alive during the summer 
months and settle down soon after leaving the protection 
of the mother. They either remain fixed from that time or 
occasionally move about until they are half grown. There 



Citrus Insects and their Control 419 

may be several generations in a season, as they require from 
sixty-five to ninety days to mature in summer. The scales 
often crowd so thickly on the leaves or along the stems as 
to overlap each other. The body of the mature female is 
oval, flat, and soft, varying in color from a dark straw yellow 
to brown, often with deeper markings. The male scales 
are much smaller and lighter in color, the mature form 
emerging as a winged insect. 

As stated above, this insect is seldom serious, but occasion- 
ally it happens that the parasites do not effectively control it, 
and it becomes necessary to fumigate or spray. 

Citricola or Soft Gray Scale (Coccus citricola) 
During the past five years a scale supposed to be a variety 
of the soft brown has caused much damage to citrus trees 
both in the coast country and interior valleys. Recently 
the insect has been described as a distinct species. 1 

The citricola scale excretes large amounts of honey-dew 
which becomes covered with sooty mold, necessitating the 
washing of the oranges. The presence of the scale is usually 
first noticed in July and August, when the sooty mold is 
forming. In the spring the adult females can be observed 
on the smaller twigs and branches, often being so numerous 
as to overlap each other and cause the twig to appear twice 
as large in diameter as ordinarily. This scale is not fatal 
to the tree, but saps its vitality and results in small crops of 
undersized sooty fruit. 

The adult female is grayish in color, usually about one- 
fourth inch long and about three-sixteenths wide, and elongates 
oval in shape. Eggs are laid during May and June and 
hatch immediately. In fact, in some cases the eggs hatch 
before they are laid, and the young are born alive. The 
1 Roy E. Campbell, Entomological News, June, 1914. 



420 Citrus Fruits 

parasites of the citricola scale do not control it effectively, 
and it has increased in the citrus orchards at an alarming 
rate. The chief method of control is by fumigation, which 
is done in July and August at the time when the greatest 
percentage of young scales are susceptible to the gas. 

Hemispherical Scale (Saissetia hemisph&rica) 

Although this scale is not a serious pest in citrus orchards, 
it sometimes becomes abundant on trees growing near the 
coast. It attacks the twigs and leaves, upon which it quite 
commonly settles along the very edge. It may be distin- 
guished from the black scale by the absence of the letter H 
on the back, its regular oval shape, and polished brown 
surface without markings. The same control measures 
used for the black scale are also efficacious for this species. 

Greedy Scale (Aspidiotus rapax) 

This species is of only minor importance as a citrus pest 
but sometimes attacks the twigs and may be found upon 
fruit remaining upon the trees from the previous season. 
As its name implies, it seems to have no choice of host plants, 
but thrives on both wild and cultivated shrubs or trees. The 
mature scale is gray or almost white and somewhat trans- 
lucent, showing the yellow body of the insect beneath. It 
is ordinarily associated with other species on citrus trees 
and remedial measures directed against this scale alone are 
seldom if ever necessary. 

Oleander Scale {Aspidiotus hederoe) 

The oleander scale is another species which only occasion- 
ally attacks citrus trees. It sometimes appears on lemons, 
usually on tree-ripe fruit, and the common name of " lemon 



Citrus Insects and their Control 421 

peel scale" has been applied to it. Although its normal 
color varies from light to dark gray, it may assume a reddish 
tinge when found on lemons and may then be mistaken for 
the red scale. 

Citrus Mealy Bug (Pseudocoecus citri) 

The mealy bug does not have to be reckoned with as a 
continuous pest in California citrus orchards. When climatic 
and other conditions are favorable, it becomes a very serious 
citrus insect and is quite difficult to control. It is found in 
all the citrus regions of the state, but has been particularly 
troublesome in Ventura and San Diego counties. It not 
only attacks the leaves and branches, but seems to be espe- 
cially fond of the fruit, often collecting in masses on both 
oranges and lemons. When concealed in the navel of the 
orange or around the stems of lemons, the insects may escape 
detection and continue to breed while the fruit is in storage 
or on the way to market. 

The honey-dew excreted by the mealy bug is very sticky 
and makes the task of cleaning the fruit exceedingly difficult. 

From three hundred and fifty to four hundred eggs are 
deposited, mostly during the fall and early winter, in a mass 
of loose, cottony fibers, excreted at the time by the female. 
The eggs hatch in eight to ten days during the summer months, 
and in about sixteen days during the winter. The young in- 
sects move about actively, the distance depending upon the 
amount and condition of the food supply. The females 
continue to move about during their lifetime, but the males 
form a cocoon and go through a stage of transformation and 
emerge in six weeks as two-winged insects, at which time the 
females are about half grown. The females require about 
two and a half months to develop, often commencing to 
produce eggs before they reach full size. The full grown 



422 



Citrus Fruits 



mealy bugs are about one-fourth of an inch in length and con- 
spicuously clothed with a white, mealy excretion. They 
have a border of short appendages around their bodies, the 

posterior appendages 
being but little longer 
than the lateral. They 
have the habit of 
settling down in pro- 
tected places such as 
the bases of the leaves 
and fruit stalks, often 
causing the leaves and 
young fruit to drop 
prematurely. 

The mealy bug 
passes the winter in 
the egg stage, but on 
account of the uneven 
hatching during the 
warm weather of 
southern California, 
usually all stages may 
be found during the 
winter season. 

On account of the 
habit which the mealy 
bugs have of secreting 
themselves in pro- 
tected places, control 
Fig. 144. — Citrus mealy bug. measures by means of 

spraying are difficult. They seem to be quite resistant 
to fumigation, and unless scale insects are also present 
in sufficient numbers to require fumigation, such treat- 




Citrus Insects and their Control 423 

ment is not recommended. The greatest success has been 
obtained by the use of distillate emulsion spray, ten to 
fifteen gallons being applied to an ordinary tree. The 
emulsion consists of four gallons of distillate oil, one gallon 
of liquid soap to two hundred gallons of water. If the in- 
sects are abundant, it may be necessary to spray two or 
three times. The best time for application is during the 
winter when there are large numbers of egg masses, or in 
the spring when the young have been hatched. 

There are several predaceous insects as well as parasites 
which assist in controlling the mealy bug; these include 
different species of ladybird beetles, lace-wing flies, and 
internal parasites. 

Citrus Red Spider ( Tetranychus mytilaspidis) and Six Spotted 
Mite (T. sexmacidatus) 

There are two species of red spiders which attack citrus 
trees in California. They occur throughout the citrus dis- 
tricts and rank second to scale insects as citrus pests. They 
injure the plant by sucking the juices from the tissues, 
giving a characteristic mottled and sickly appearance to 
the leaves. The green fruit also is attacked, and an objec- 
tionable pale silvery color produced. Red spiders also 
sometimes injure lemons in packing-houses while the lemons 
are in storage. 

Since the citrus red spider is the one usually responsible 
for injury to citrus trees, that species is the one which will 
be discussed here. The common red spider or six spotted 
mite does not limit itself to citrus as a food plant, although 
in San Diego County it is sometimes a more important 
lemon pest than the other species. 

The citrus red spider was introduced from Florida on 
nursery stock about 1890 and has been a serious pest since 



424 Citrus Fruits 

1895. It is very minute, red in color, and often becomes so 
abundant on a leaf as to give it a reddish hue also. The red 
eggs are placed separately on the leaves, and are elevated 
upon short stalks held in place by radiating guy threads 
fastened to the surface of the leaf. The number deposited 
by each female will average about thirty. During the 
month of May and the summer months, about ten days are 
required for hatching, although it may take three weeks in 
the cooler seasons. The young begin to feed immediately 
and grow rapidly, only twelve days being required to reach 
maturity and begin egg-laying. 

Sulfur is the universal remedy for red spider. It was 
first applied in the dry powdered form, dusted over the trees 
either with a small bellows or a power blower, preferably 
when the foliage was damp. Lime-sulfur sprays have recently 
met with great favor and are being extensively used. Natural 
enemies, such as predaceous beetles and the lace-wing flies, 
assist materially in reducing the damage due to red spider. 
The commercial lime-sulfur preparations are commonly 
used, one gallon to thirty-five gallons of water being recom- 
mended. About six or seven gallons of the solution are 
required for the ordinary tree, making the cost about fifteen 
cents, considerably less than the cost of fumigation. 

Silver Mite (Eriophyes oleivorus) - 

The silver mite is not a true insect but belongs to the same 
class as the red spider. It was introduced from Florida into 
San Diego County in 1889 and its ravages have been restricted 
to a section of that county. The mite attacks the bark, 
foliage, and fruit, producing the greatest injury to the 
fruit. Green lemons if attacked take on a silvery appear- 
ance, due to the extraction of the oil and green coloring 
matter from the cells of the rind. On oranges it produces 



Citrus Insects and their Control 425 

a russet color of the fruit, hence it is sometimes known as 
the rust mite. 

The eggs of the silver mite are deposited singly or in small 
clusters on the leaves or fruit and hatch in from five to 
fourteen days, depending upon the season. The young 
mites grow rapidly, only eight to ten days being required to 
reach maturity, and in the course of the season they may 
become very abundant. The adults are scarcely visible 
to the naked eye, but their presence is indicated by the 
characteristic silvery color produced on the lemons as well 
as on the leaves. Such fruit is either thrown out as culls 
or utilized in making by-products. The control measures 
are the same as for the red spider. 

Orange Thrips (Euthrips citri) 

Thrips are very common insects in nearly all kinds of 
flowers, including citrus. Blossoms shaken over the hand 
will generally dislodge a number of both young and adults ; 
the latter, being very active, either jump or fly away. Thrips 
which occur in flowers, however, do not usually belong to 
the above species, as there are numerous kinds which do 
comparatively little damage. The true orange thrips are most 
abundant in Arizona and in the San Joaquin citrus district, 
but are also occasionally injurious in the Redlands district. 

The presence of the thrips is usually evidenced by their 
work upon the young leaves, which are commonly distorted 
in growth and leathery. On the fruit they produce scars 
which may form regular rings around the stem end, or appear 
in irregular spots over the surface. The mouth-parts of the 
thrips are intermediate between the sucking and biting 
insects and consist of a chafing or rasping rather than a biting 
organ, which accounts for the scars produced upon the leaves 
and fruit. Although not injuring the edible qualities of the 



426 



Citrus Fruits 



oranges, such scars affect the market value by placing the 
fruit in poorer grades. 

The adult thrips hibernate over winter in protected places 
and appear about the middle of April, feeding upon the ten- 




Fig. 145. — Scars due to citrus thrips. 

der leaves. The eggs are produced throughout the summer 
months and hatch in six to ten days after being deposited. 
The young are very active and resemble the mature forms, 
except that they are much lighter in color and without 
wings. It has been estimated that there are from eight to 



Citrus Insects and their Control 427 

ten generations a year in the San Joaquin Valley, about 
twenty days being required for development from egg to 
adult, and about twenty-three days the average length of 
life after reaching maturity. 

The most effective remedy for thrips seems to be spraying. 
The formula recommended by the U. S. D. A. Bureau of 
Entomology is as follows : 

Commercial lime sulfur (33°) . 2§ gal. 

Black leaf extract . . . 2 gals, of 2f% or 14 fluid oz. of 40% 
Water 200 gal. 

It is necessary to use a very strong pressure, 175 to 200 
pounds, in applying the spray so that all parts of the tree shall 
be reached. The first application should be made as soon 
as the petals have fallen ; a second and third spraying is 
advisable at intervals of about ten days. 

While spraying for thrips has been practiced on a large 
scale, it is a fact that at present but little spraying is done. 
Inasmuch as the thrips is severe only in occasional years, 
most growers prefer to take the risk rather than to go to 
the expense of spraying. 

Melon Aphis or Plant Louse (Aphis gossypii) 

This species of plant louse is very common throughout 
California on melons, gourds, and weeds, and at times becomes 
abundant on citrus trees, especially in early spring. They 
attack the tender young growth and under sides of the leaves, 
causing the latter to curl. Such infestations are rarely very 
extensive, the injury being usually confined to a few scattered 
branches. Unfavorable weather, ladybird beetles, and other 
natural enemies ordinarily keep the numbers of plant lice 
reduced. In case they are doing much damage to young 
nursery stock, however, a spray of nicotine extract or weak 
soap solution will be found effective. 



428 Citrus Fruits 



Orange Tortrix (Tortri.r citrana) 

The orange tortrix attacks a great variety of plants, both 
wild and cultivated, feeding mostly upon the leaves, which it 
fastens together by silken threads. It was first described 
in 1889, and has been reported occasionally as injuring various 
plants, including the fruit of orange trees. In 1910, its injury 
to oranges in southern California, especially in Los Angeles 
County, caused the growers no little alarm, as high as ten per 
cent of the fruit being found wormy in some of the packing- 
houses. The damage is done by the larva or small worm 
which burrows its way into the fruit, seldom going deeper 
than the rind, however. These holes in the rind not only 
cause the fruit to be graded as culls but also provide an 
entrance for the germs of decay. 

The eggs are deposited on leaves or fruit in small masses 
of from ten to thirty-five eggs, overlapping each other like 
fish scales. They hatch in about twelve days and the larvae 
feed at first upon the surface of the fruit or on the leaves but 
later burrow into the rind, where they remain until full grown. 
At this time they are about half an inch in length. They 
form a chrysalis either in the burrow or in a protected place 
outside, and at the end of ten days emerge as yellowish gray 
moths, less than half an inch long. According to observations 
which have been made in the orchards, there are probably 
three generations of the tortrix in southern California. 

So far no effective method of control by insecticides has 
been worked out. Fortunately the serious outbreaks are 
spasmodic, occurring only in occasional years. Often they 
are confined to small localities or even particular groves. 
Perhaps the most practicable remedy is to destroy the fallen 
fruit before the larvae have emerged, and also to destroy the 
wormy culls from the packing-houses. 



Citrus Insects and their Control 



429 




Fig. 146. — Full- 
er's rose beetle. 
(Enlarged.) 



Fuller's Rose Beetle (Aramigus fulleri) 

The injury done by Fuller's rose beetle is 

most serious on young trees and young, ten- 
der foliage of larger trees. The adult beetles 

live on the foliage, feeding mostly at night, 

while the larva? or grubs feed on the roots, 

so that both stages do considerable damage 

where they are abundant. The beetle is 

wingless, grayish brown in color, and about 

three-eighths of an inch in length ; the 

head tapers into a short snout. 

Since the adults are unable to fly, they 

may easily be pre- 
vented from reach- 
ing the foliage of 
trees by bands of 
cotton or tangle- 
foot placed around 
the trunks. The 
band of cotton 
about four inches 
wide is wrapped 
around the trunk 
and tied tightly 
along the lower 
edge ; the upper 
half is then pulled 
down over the 
lower so that it 
flares out a little 
from the trunk. 
This remedy is 
Fig. 147. — The work of Fuller's rose beetle. especially effective 




430 



Citrus Fruits 



where old trees have their tops removed for top-working. 
In such cases a few beetles may quickly destroy all the buds 
inserted in the stump. 




Western Twelve-spotted Cucumber Beetle (Diabrotica soror) 

This species of Diabrotica is liable to attack the leaves and 
flowers of almost any kind of plant which it happens to find. 

The young and tender 
foliage of citrus trees is 
often seriously injured 
by the beetles although 
orange leaves seem to 
be much preferred to 
those of the lemon. 
The beetles appear in 
such numbers at certain 
seasons that control 
measures must be used 
to protect young plants 
from their attacks. 
During the early morn- 
ing, while they are in- 
active, the beetles are 
quite easily jarred from 
the trees into a vessel containing kerosene or on to a tarred 
screen. Spraying will also be found effective, arsenate of 
lead, eight pounds to two hundred gallons of water, being 
recommended. 

Katydids often produce scars on oranges such as are 
shown at Fig. 148. The insects eat away the exterior of the 
rind while the fruit is quite small. As the fruit increases in 
size the scars enlarge. 



Fig. 14S. 



• Scars on rind of orange caused 
by katydid. 



CHAPTER XXIII 
INSECT CONTROL BY FUMIGATION 

The control of insects by fumigation was first seriously 
considered in California in 1886 when the cottony cushion 
scale was ravaging the orchards of Los Angeles County. 
At the request of certain citrus growers, E. W. Hilgard of 
the California Experiment Station detailed F. W. Morse 
of the University of California to carry on an investigation 
looking toward the control of the scale by fumigation. 
Mr. Morse began work in April, 1887, and soon found 
that hydrocyanic acid was the most effective of any of 
the gases experimented with. The results achieved by 
Morse attracted the attention of the Los Angeles County 
Board of Horticultural Commissioners, who offered to 
pay the expenses of a more comprehensive investigation. 
This was made later in the same summer, and the results 
published as bulletins 71 and 73 of the California Experi- 
ment Station dated June 12 and August 27, respectively. 

It then became known that D. W. Coquillett had dis- 
covered the value of hydrocyanic acid for fumigation in 
the fall of the previous year, but had kept the fact secret 
while endeavoring to perfect the method for the purpose 
of securing a patent. Later Coquillett accepted an 
appointment as Special Agent for the Division of Ento- 

431 



432 



Citrus Fruits 



mology of the U. S. Department of Agriculture and con- 
tinuing his experiments with fumigation published a series 
of reports on the subject which proved of great value to 
the industry. 

About the year 1901, a much cheaper method of con- 




Fig. 149. — A fumigation demonstration. 



trolling scale by spraying with distillate oil was intro- 
duced. It was soon found, however, that spraying was 
much less effective than fumigation. The black scale 
increased to an alarming extent, and the thorough wash- 
ing made necessary by the sooty mold caused a great 
increase in the decay in transit. As soon as it was proven 
that a large proportion of the decay in transit was due 



Insect Control by Fumigation 433 

primarily to the presence of black scale in the orchards, 
the growers took a renewed interest in fumigation. R. S. 
Woglum of the U. S. Department of Agriculture was 
detailed to make a comprehensive investigation of the 
whole subject, which he did with marked success. Wo- 
glum's work in California has been continued for seven 
years and has resulted in a number of very valuable pub- 
lications and much good to the industry. 

The methods of fumigation have thus been developed 
until now it may almost be considered a science by itself. 
The practice has spread to other parts of the world, and 
bids fair soon to become the almost universal method of 
controlling scale insects on citrus trees. Woglum states 
that in the five southern counties of California the amount 
of money spent on fumigating citrus trees during an 
average season 1909-1910 approximated $1,000,000. 
This statement not only gives some idea of the extent to 
which fumigation is practiced, but it shows what a fearful 
tax and unnecessary handicap the presence of scale in- 
sects place on the citrus industry. 

The great success of hydrocyanic acid gas in controlling 
scale insects is due to the ease of its generation, and its 
exceedingly poisonous nature. The chief difficulty has 
been to find the exact dosage which will give maximum 
results in the numbers of insects killed, and at the same 
time produce a minimum of injury to the tree. The 
different scales vary in their susceptibility to the gas, and 
separate dosage tables have now been worked out for all 
the important scales. For a long time a serious obstacle 
was the frequent burning of the leaves and fruit. This 
was largely overcome by confining all fumigation to the 
2f 



434 Citrus Fruits 

night, when lower temperatures prevailed. This was so 
successful that now all fumigation is done at night. 

Tent fumigation of citrus trees in California at the 
present time is practically limited to districts in the 
southern part of the state, although it is being used to 
some extent in Tulare County in controlling the citricola 
scale. The cost of fumigating the average sized tree is 
about 30 cents, which means an expense to the growers of 
$30 to $40 an acre. Fumigation may sometimes be 
necessary every season ; if thoroughly done, however, it 
may be necessary only once in two or three years. 

Various systems are in operation among the growers' 
for carrying on the work of fumigation. A large part is 
performed by contractors who make a business of fur- 
nishing the materials and doing the work for a stipulated 
sum. Local associations in which the growers cooperate 
for mutual protection and benefit, often own fumigating 
outfits and treat the infested orchards belonging to their 
members. Such work is usually done under the super- 
vision of a county inspector who sees that the fumigation 
is properly done. In San Bernardino County, until quite 
recently, the Horticultural Commission owned several 
hundred tents and performed annually an immense amount 
of fumigation wherever needed. This finally became 
such a great burden to the Commission that the service 
has been discontinued and the work is now done in 
various other ways. In many cases, private individuals 
or companies having a large acreage in citrus trees 
keep their own fumigating equipment. At Highlands, 
California, an agreement has been made by a number of 
growers in the district for the sole purpose of protecting 



Insect Control by Fumigation 435 

their orchards from scale and other insect pests, each 
grower agreeing to share part of the expense of fumigation, 
whether his own orchard is infested or not ; the point 
being that the grower should rather combat scale in some 
orchard other than his own. 

FUMIGATION BY HYDROCYANIC ACID GAS 

Fumigation by hydrocyanic acid gas is accomplished 
by covering the trees at night with air-tight tents, and 
placing under them earthenware gas generators contain- 
ing a mixture of sulfuric acid, water, and either potas- 
sium or sodium cyanide. 

Tents 

Fumigation tents are ordinarily made of the best eight 
ounce army duck obtainable, and vary in size, twenty-foot 
tents being large enough for small trees and thirty-six- 
foot tents for the ordinary sized tree. For very large trees, 
much larger tents may be necessary, although smaller 
sized ones can be lapped over when such trees are to be 
fumigated. In order to save material the tents are made 
in the shape of an octagon. New tents are usually dipped 
in a solution of oak bark extract of tannin, one pound to 
five gallons of water heated nearly to the boiling point. 
The tents are immersed in this hot solution for twenty 
to thirty minutes, after which they are spread out on the 
ground to dry. This treatment is practiced to make the 
tents proof against mildew, but is not absolutely neces- 
sary in the climate of southern California, if proper care 
of the tents is taken in the field as well as in storage. 
The average length of life of a fumigation tent is three or 



436 



Citrus Fruits 



four years, although the period of usefulness can of course 
be greatly extended by careful handling. 

In the old system of fumigation the method of calcu- 




I II II II 1 1 I I II 



■OVONCOO^S! 55!5 55^ 



s 

6 
-7 
8 
9 
■10 
II 
-12 
13 
14 
IS 
16 
17 



5 

6 

7 

8 

9 

10 4-/0 

// - -// 

12 - -12 

13 +13 
14 
IS 



6 

7 

8 

+9 



16 -16 
/7 -17 



Fig. 150. — Method of marking fumigating tent. (After Woglum.) 

lating the dosage for a tree was mostly guesswork, the 
operator gauging the size of the tree by eyesight and 
basing the dosage upon previous experience. Such 
methods sometimes produced fairly good results but in 



bisect Control by Fumigation 437 

general the work was very irregular and poor. The tents 
now in use are plainly marked, as shown in the accom- 
panying diagram, the measurements being -'marked in feet 
from the center of the tent. When the tent is enfolding 
a tree, the distance over it can readily be determined by 
adding the number that touches the ground on one side 
of the tree to the number that touches the ground on the 
opposite side. The two auxiliary lines are necessary, as 
in actual practice the middle line may not fall over the 
middle of the tree but to one side, and in such a case the 
line nearest the center is used for measurement. The two 
side lines may be either three or four feet from the middle 
line. 

Equipment of Tents 

For elevating the tents over the trees, either poles or 
derricks are used, the latter being necessary only for very 
tall trees. Fourteen- and sixteen-foot poles are most 
commonly used. One end is sharpened to prevent its 
slipping on the ground. To the other end is fastened a 
rope about three feet longer than the pole. Sometimes 
rings are attached to the edge of the tent, and these are 
slipped over the ends of the poles; it is usually more 
satisfactory, however, to double-lap the edge of the tent 
over the ends and secure it firmly by a half-hitch of the 
pulling ropes. 

Generators 

Another part of the outfit is the set of earthen jars or 
containers called generators. These are made especially 
for the purpose, usually without covers, and of two gallon 
capacity. The two gallon size is preferred, as it is large 



438 Citrus Fruits 

enough to accommodate 20 ounces of cyanide in medium 
sized lumps without boiling over. When trees requiring 
more than this amount are to be fumigated, two or more 
generators may be used under one tent. Generators with 
lids are desirable as the lids not only aid in throwing the 
gas outward but prevent spattering of the acid on to 
the tent. Acid holes in tents cause serious leakage, 
reduce efficiency, and necessitate frequent and expensive 
patching. So far, however, no lids manufactured have 
proved entirely satisfactory. The most improved type of 
generator has the outside of the bottom flat as usual but 
the inside of the bottom is cup-shaped, with the depres- 
sion in the center. This is a great advantage when work- 
ing with very small trees as it assures a more thorough 
decomposition of the small quantity of cyanide used for 
each charge. 

Still another part of the fumigating outfit is the supply 
cart in which are carried the cyanide, sulfuric acid, water, 
scales for weighing the cyanide, graduated glass for meas- 
uring the acid and water, rubber gloves, dosage schedules, 
and lantern. There is on the market an excellent supply 
cart designed especially for this purpose which is highly 
desirable where funds will permit, although simpler and 
less expensive carts answer very well. 

Cyanide 

Potassium cyanide was used in all fumigation work until 
recently. Now, however, sodium cyanide is used exclu- 
sively for the reason that it is not only cheaper but will 
supply a larger amount of hydrocyanic acid gas. The 



Insect Control by Fumigation 439 

cyanide should be kept dry in storage and exposed to the 
air as little as possible, since moisture decomposes it. 



Acid 

Sulfuric acid for fumigating should be about 66° 
Baume, which is approximately ninety-three per cent 
pure. It is sold either in iron drums containing about 
2000 pounds or in glass carboys of about ten gallons 
capacity. On account of its corrosive action glass or 
earthenware containers are used for distributing the acid 
in the field. A replaceable copper or glass pipe fitted into 
the bottom of the container on the supply cart is con- 
nected with a rubber tube bearing a large pinch-cock for 
regulating the flow. Care must be used in handling the 
acid as it will quickly burn wherever it comes in contact 
with the skin ; for this reason, rubber gloves are advisable. 

It has been found that the 1-1 §-2 formula recom- 
mended by the Bureau of Entomology is most economical 
and produces a complete reaction. This formula calls 
for 1 fluid ounce of commercial sulfuric acid, l| ounces 
(avoirdupois) 129 per cent sodium cyanide, and 2 fluid 
ounces of water. The water is measured and placed in 
the generator first, then the acid is measured and poured 
into the water. Lastly, when everything is in readiness, 
the cyanide is weighed and placed in the • solution, the 
operator quickly retreating and closing the tent. 

The addition of water to the acid is very important. 
It dilutes the acid and raises the temperature of the 
mixture, thus accelerating the evolution of gas. The by- 
product resulting from the reaction is sodium sulfate. 



440 Citrus Fruits 

a solid. The water dissolves this solid as fast as it is 
formed and prevents it from forming a coating over the 
lumps of cyanide and retarding the reaction. If sufficient 
water is not used, the sulfate will solidify, thus "freez- 
ing" the residue, as it is called. This necessitates extra 
labor in emptying the generators. When concentrated 
acid is diluted with an equal amount or more of water, 
nearly pure hydrocyanic acid is given off. If the con- 
centrated acid is used without water another gas known 
as carbon monoxide is formed. 

The cyanide should always be used in lumps about the 
size of a hen's egg. If finely powdered cyanide is used, the 
reaction is too violent and endangers the operators. If 
the cyanide should be dissolved in water before the acid 
is added, the reaction will be so violent as to be classed 
as an explosion, greatly endangering the operators and 
injuring tents and trees. Paper bags are no longer used 
for depositing the cyanide in the generators. Cakes of 
compressed cyanide weighing one ounce each are now on 
the market, and have proven very satisfactory and 
convenient. Under proper conditions the evolution of 
gas will have been completed in about five minutes. 

Operation 

An orchard requiring fumigation should be thoroughly 
examined regarding the slope of the land, length of tree 
rows, convenience to water supply, smoothness of the 
ground over which the supply cart is to be drawn, and 
similar factors which influence the ease of operation. A 
tent and a generator are unloaded at each tree and the 



Insect Control by Fumigation 441 

tents unfolded on the side away from the direction in 
which they are to be moved. Commencing at one end 
of the row, the tent pullers fasten the two poles to the 
edge of the tent in the manner previously described, place 
the sharpened ends of the poles on the ground at the sides 
of the tree opposite the trunk, and holding the bottom 
of the pole to the ground with one foot, pull on the rope. 
When the poles are so elevated that they no longer slip, 
each puller moves away from the bottom of the pole and 
out from the tree so that the continued pulling will bring 
the edge of the tent over the tree and down on the other 
side. When thus covered, the edge of the tent should 
be kicked in so that it hangs evenly all around and does 
not inclose unnecessary space. After the tree has been 
fumigated the required length of time, the tent can be 
pulled over on to the next tree by this same process with- 
out lowering it entirely to the ground. 

The next step in the process is the calculation of the 
approximate space inclosed by the tent and the proper 
dosage to use. Schedules given on pages 450 to 453 
indicate the proper dosages for the principal citrus in- 
sects which require treatment. Knowing the distance 
over the tree (found as previously directed) and the cir- 
cumference of the tent near the base, one will have no 
difficulty in using the tables. The number found at the in- 
tersection of the vertical and horizontal rows on the table 
indicates the number of ounces of cyanide to be used. 

With the ordinary outfit of five men, the work may be 
distributed as follows : two men handle the tents, a third 
takes the measurements and calls them out to the men 
at the supply cart, who immediately consult the dosage 



Insect Control by Fumigation 443 

table, weigh out the cyanide, and measure the sulfuric 
acid and water into the generator. 

While the cyanide man lifts the edge of the tent, the 
other places the generator underneath. The former then 
puts in the cyanide and drops the tent. While the chemi- 
cal men are thus applying the proper dosage to one tree, 
measurements are being made on the next and the process 
is repeated until the entire row is fumigated. 

Fumigation gangs are usually equipped to handle about 
thirty tents at a " throw," as they call it. When kept 
busy these 30 tents are "thrown" or moved once in every 
forty-five minutes or once every hour as the variety of 
scale will determine. Thus, except with very large trees, 
the number of trees fumigated per night does not vary 
according to the size of the trees, the difference simply 
being a difference in the time the men have to rest between 
throws, as all must be left over the trees a stated period 
of time. As a rule fumigators, when the nights are favor- 
able, begin work about 5 p.m., and if the night is not too 
cool or a fog arises, will work till G a.m., giving a twelve- 
hour night if an hour is taken off at midnight for lunch 
and rest. Thus with twelve-hour nights and throws every 
hour, a gang operating 30 tents will fumigate about 32 
acres provided the trees are planted regularly twenty feet 
apart each way. Fumigating in short rows, on contours, 
or in rough ground is slower, of course. 

Season of Fumigation 

The time of year at which fumigation is done depends 
upon two factors, the life-stages of the scale insect and 



444 



Citrus Fruits 



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448 Citrus Fruits 

the condition of the tree and fruit. Most of the fumiga- 
tion in California is carried on between the latter part of 
August and the middle of January, as during these months 
the black scale is most successfully reached and the fruit 
is large enough to escape the injury which sometimes 
occurs when it is young and tender. As previously men- 
tioned, fumigation is ordinarily done at night when the 
air is cool. Occasionally the work may be done on dark 
cool days, but day work is quite apt to result in burned 
foliage and fruit. Fumigation is not advisable when the 
temperature falls below 38° F. or rises above 65° F. as 
the operator runs some risk of injuring the trees if the 
work is done much outside these limits of temperature. 
Another natural factor which operates against successful 
work is a strong breeze, which may either hasten the escape 
of the gas from the tent or greatly injure the side of the 
tree on which the gas becomes densest. Cases of serious 
injury to trees which were said to have resulted from 
fumigation when the foliage was wet have been frequently 
reported. Careful experiments along this line, on the 
other hand, show that the presence of moisture on the trees 
can be ignored so far as direct action of the gas is con- 
cerned. Due, however, to the fact that the tents become 
so heavy and retain so much more of the gas on a wet 
than on a dry night, it is advisable to stop fumigating 
after the foliage and tents become thoroughly damp. 

The insect pests against which fumigation is generally 
directed are the black, purple, red, yellow, and citricola 
scales. The susceptibility of these scales to the gas varies 
more or less, and accordingly several dosage schedules have 
been worked out. Experiments by Woglum in fumigating 



Insect Control by Fumigation 449 

for the purple scale demonstrated that the best results 
were obtained by one and one-half ounces of potassium 
cyanide to every one hundred cubic feet of air space 
under the tent, the fumigation continuing for one hour, 
by the end of which practically all gas had escaped. 
This is designated as dosage schedule A and upon this 
the other schedules are based. The three-quarter schedule 
for 129 per cent sodium cyanide is the one almost univer- 
sally used at the present time. 

Dosages 

For the purple scale, dosage schedule No. f sodium 
cyanide should be used with an exposure of one hour. 

For red and yellow scales, dosage schedule No. f is 
recommended with an exposure of forty-five minutes to 
one hour. 

For black scale, the dosage varies. When the insects 
are in the young and tenderer stages, f of schedule A is 
sufficient, and it is during these stages that fumigation is 
advisable. 

Dosage schedules A for sodium cyanide and No. 110 per 
cent A are reproduced on pages 446, 447 and 444, 445 
respectively. They have been tested out experimentally 
in actual field operations by Woglum. Copies of these 
schedules printed on cardboard may be secured from 
the U. S. D. A. Bureau of Entomology, or from dealers 
in fumigators' supplies. While using the dosage sched- 
ule in the orchard, it should be framed with a clear 
celluloid or glass cover, as otherwise it will soon become 
so worn and dirty as to be illegible. 
2g 



450 



Citrus Fruits 



New Woodworth Dosage Table 

C. W. Woodworth has recently suggested a new way 
of calculating dosage which appears to have the advantage 
of greater simplicity and accuracy. 



Dosage Table — Sodium Cyanide 



Relative Size 


Dose 
Purple Scale 


Dose 
Black Scale 




64 ft, 


40 oz. 


20 OZ. 




61 ft. 


46 oz. 


18 oz. 




58 ft. 


32 oz. 


16 oz. 




55 ft. 


28 oz. 


14 oz. 




52 ft. 


24 oz. 


12 oz. 




50 ft. 


20 oz. 


10 oz. 




47 ft. 


18 oz. 


9 oz. 


Minimum Dose 


44 ft. 


16 oz. 


.8 oz. 




41 ft. 


14 oz. 


7 oz. 


Leakage 


38 ft. 


12 oz. 


6 oz. 


•40% 


36 ft, 


10 oz. 


5 oz. 




33 ft. 


9 oz. 


4^ oz. 




30 ft. 


8 oz. 


4 oz. 


.35 % 


28 ft. 


7 oz. 


3i oz. 




26 ft. 


6 oz. 


3 oz. 




24 ft. 


5 oz. 


2| oz. 


.30% 


21 ft, 


4 oz. 


2 oz. 




19 ft. 


3i oz. 


If oz. 




16 ft. 


3 oz. 


l\ oz. 


.25 % 




2\ oz. 


l\ oz. 






2 oz. 


1 oz. 


•20% 




1^ oz. 


\ oz. 






1 oz. 


2 OZ. 


• 15% 




\ oz. 


\ oz. 


• 10% 



(Relative size equals distance over plus 1 for each 5 ft. of 
difference between measurements.) 



Insect Control by Fumigation 451 

In explanation of this new system Prof. Woodworth 
has submitted the following : 

" The possibility of adding to the distance over an 
amount dependent on the difference between the two 
measurements which will indicate the proportionate size 
of a tent gives us what we may call the ' relative size ' of 
the tent. If the proportions of a tent remained constant, 
the difference over could then be taken as the relative size. 
Since the distance around always equals or exceeds the 
distance over, we may select as standard a tent with these 
two measurements equal. The amount to be added to 
this to allow for wider and shorter tents is one-fifth of the 
difference between the two measurements. Thus a tent 
20 X 30 would have a relative size of 22, and should have 
a dose equal to that of a tent 22 X 22. 

' The adoption of this plan of relative sizes makes it 
possible to present a table of dosage in a very simple 
form, and to make the adjustments for different degrees 
of leakage also very easy. 

" In the foregoing table the first column gives the rela- 
tive sizes corresponding to the series of doses shown in 
the second and third columns suitable for tents having 
the average leakage of 25 per cent. 

" The adjustment for leakage is equally simple. Oppo- 
site each per cent given in the table is the minimum dose. 
No matter how small the tree, if a tent leaks 40 per cent, 
the dose for purple scale should not be less than 12 oz. 
Indeed, it is unwise to attempt to fumigate with a tent 
of this degree of leakage except when big enough to hold 
a sufficient body of gas without its being too concentrated 
at the time of generation for the safety of the tree." 



452 Citrus Fruits 

Costs 

Cyanide costs by the ton about 22 cents a pound. Con- 
tract fumigators usually furnish the cyanide at 30 cents a 
pound, including the acid for generation. The sulfuric 
acid alone costs about 1| cents a pound. Laborers receive 
pay by the hour. The rate is usually 35 cents an hour, 
while the foreman receives 50 cents an hour. Most trees 
fumigated require between five and eighteen ounces of 
cyanide. A supply cart completely equipped may be had 
for about $35. Two gallon generators cost about 45 
cents each. Tents cost from $12 to $50 each, according 
to size. The thirty-six foot tent costs ready-made from 
$25 to $30 each. The cost of thirty 45-foot tents of special 
7-ounce drill, together with the other equipment necessary 
to complete the outfit, will cost about $1400. 

Recently a fumigating machine has been invented 
which quickly generates the gas in a large metal drum by 
mixing a water solution of cyanide and acid. The gas is 
discharged directly into the tent through a four-inch hose. 
The use of this machine makes generators unnecessary 
and prevents all acid holes in the tents. It is now being 
widely experimented with. 



CHAPTER XXIV 

VARIOUS ORCHARD PESTS AND THEIR 
CONTROL 

There are several pests other than insects with which 
citrus growers are apt to have to deal. A knowledge of 
the habits of animals such as gophers and ground squirrels 
is necessary before intelligent methods of repression can 
be adopted. Recently the citrus root nematode has at- 
tracted much attention, and a rather detailed account 
of its habits and life history will no doubt prove of quite 
general interest. 

Citrus Nematode (Tylenchuhis semipenetrans) 

As stated in Chapter XXI this worm has been suggested as 
the cause or one of the causes of mottled-leaf. On account 
of the popular interest in the nematode and the great diver- 
sity of opinions regarding it, space is given to a more or 
less detailed account. The data here presented has been 
largely condensed and adapted from Cobb. 1 

This citrus nematode was first noticed by J. R. Hodges of 
Covina, California, in 1912, and first mentioned in print by 
B. R. Jones. 2 A preliminary report was later published by 
E. E. Thomas of the University of California. 

1 N. A. Cobb, "Citrus-root Nematode," Journal of Agri- 
cultural Research, Vol. II, No. 3, June, 1914, pp. 217-230. 

2 Los Angeles County Hort. Com. Bull. No. 1, 1913, pp. 72- 
73. 

453 



454 Citrvs Fruits 

This species of nematode is found only on the roots of 
citrus trees although it occurs in all parts of the world where 
citrus trees have been grown for any length of time. The 
worms are very minute, being barely visible to the unaided 
eye. The males are smaller than the females and probably 
do not attack citrus roots. In fact, it is thought that the 
males do not take food while in the perfect stage. The eggs 
are large and thin shelled, and are deposited one at a time 
in batches of twelve to twenty or more, and are sometimes 
incased in gummy matter. The eggs hatch in a day or 
two into colorless larvae which make their way to the nearest 
citrus root to which the females attach themselves in more or 
less well defined groups. These groups are very quickly 
scattered along the fine fibrous feeding roots in enormous 
numbers. The effect is to sap the vitality of the tree and 
kill the feeding roots. The movements are slow and weak 
and the worms cannot migrate through the soil to any great 
distance. 

The females possess an oral spear with which they force 
the head end into the tissues of the root. That part of the 
body within the root enlarges somewhat so that it is impos- 
sible for them to withdraw. They remain fixed for the rest 
of their lives, although the exposed part of the body may be 
moved back and forth. The food consists of sap and pro- 
toplasmic cell contents. The entire life cycle occupies from 
six to eight weeks. 

A predaceous nematode of large size (Mononchus papil- 
latus) has been found to occur also in the soil about citrus 
roots. The Mononchus preys regularly upon the males and 
larvae of Tylenchulus, swallowing them whole. To what 
extent the Mononchus may be able to control the citrus 
nematode is not at present known. 

The citrus nematode affects the different stocks about 



Various Orchard Pests and their Control 455 

equally. It has so far been found in abundance on the sour, 
sweet, and trifoliate oranges and on pomelos. 

" There can be no doubt that Tylenchulus semipenetrans is 
an injurious parasite. There is conclusive evidence that it 
kills the feeding roots of citrus trees. The roots die either as 
a direct result of the attack of this parasite or of the attack 
of other organisms following in its wake ; in other words, 
the nematode is a primary cause of the death of the feeding 
roots. Many cases have come under observation in which 
it was apparent that, had it not been for the nematode, the 
roots would have remained in a healthy condition. The 
evidence along these lines is of the same character as that 
which is relied on in demonstrating injuries due to insects 
and other macroscopic parasites. 

" The extent of the damage which may properly be charged 
up against this parasite is a different matter, and it will be 
necessary to collect evidence along this line for several years 
before a final statement can be made. Up to the present 
the data obtained indicate unquestionably that the investi- 
gations should be continued." 

The citrus nematode is very readily distributed from place 
to place on the roots of nursery stock, and this is especially 
true when the trees are balled for shipment. The question 
as to just how much importance to place upon inspection and 
quarantine in connection with this parasite cannot be an- 
swered at the present time. In order to be on the safe side 
it is well for buyers to specify that the trees be free from 
nematodes. Control measures such as injecting carbon 
bisulfide and lime water into the soil are being widely ex- 
perimented with, but so far without any very promising re- 
sults. Vaile 1 has shown that nematodes are killed by sub- 
mersion in hot water at a temperature of 120° F. for ten 

1 Annual Rpt. Ventura County Hort. Com., 1913, p. 10. 



456 Citrus Fruits 

minutes. This treatment did not kill the roots entirely, al- 
though some of the fine feeding roots were injured. This 
is not considered important because when trees are trans- 
planted with bare roots they put out new feeding roots 
anyway. It is possible that some such method of treatment 
may soon be devised by which infested nursery stock may be 
freed from the pest. 

The Pocket Gopher (Geomys bursarius) 

Gophers often cause serious damage to citrus trees by 
girdling young trees at the surface of the ground and by chew- 
ing the bark from the crown roots of older trees. They are 
especially troublesome in orchards near alfalfa fields in sec- 
tions where open ditches are used for irrigation. Gophers 
will run for considerable distances over the surface of the 
ground at night, and entering an orchard without warning 
begin to dig their runways. The runs extend for long dis- 
tances underground and are vexatious nuisances when irri- 
gating. Gophers may be controlled both by poisoning and 
by trapping. 

In trapping use a small wire spring trap and set it delicately 
so it will spring easily. Then open the run under a recently 
made pile of fresh dirt and insert the trap, pushing it well 
back into the run. If the run goes both ways, put in two 
traps to make sure. Then close up the holes with grass or 
sod so that just a little light can enter. The gopher will 
soon notice the light, and in attempting to close the opening 
will be caught. It is well to attach a long string to the trap to 
prevent their being lost if pulled for some distance back into 
the hole. Any attempt to drown a gopher by turning irrigation 
water into the hole will not succeed unless the entire surface 
of the ground can be flooded as is possible in alfalfa fields. 

Strychnine is probably the most effective and safest poison 



Various Orchard Pests and their Control 457 

for general use. A sirup poisoned with strychnine is very 
easily prepared and will be found very effective. It is made 
according to the following formula recommended by the 
U. S. Bureau of Biological Survey : " Dissolve an ounce of 
strychnia sulfate in a pint of boiling water. Add a pint of 
thick sugar sirup and stir thoroughly. The sirup is usually 
scented by adding a few drops of oil of anise, but this is not 
essential. If preserved in a closed vessel, the sirup will keep 
indefinitely." This quantity will poison about thirty pounds 
of shelled corn or grain, preferably corn. The grain should 
be soaked in water overnight and then soaked for several 
hours in the poisoned sirup. The dry strychnine may also 
be used by introducing a very small quantity on the point 
of a knife into carrots, beets, sweet potatoes, entire raisins, 
or prunes. Such poisoned bait is then placed carefully in 
the freshly open holes, or in the runways. There are many 
prepared gopher poisons on the market which may be pur- 
chased if one does not care to go to the trouble of mixing the 
strychnine as directed. 

The use of carbon bisulfide for killing gophers is recom- 
mended where the soil is moist and the burrows not too ex- 
tensive. In dry soil, the gas escapes too rapidly to make its 
use effective. The bisulfide may be poured over a bunch of 
cotton waste or other material and this pushed quickly into 
the burrow, which should be closed at once. Since carbon 
bisulfide is highly inflammable a very common method of ap- 
plication is to ignite the cotton waste after it is placed in 
the burrows as deeply as possible ; the gases produced by 
ignition are poisonous and seem just as effective a killing 
agent as the liquid bisulfide. On account of the danger of 
explosion to the operator and the liability of starting grass 
fires, the use of bisulfide by ignition is not so advisable as by 
the former method. Special injectors for forcing the bisulfide 



458 Citrus Fruits 

into the burrows are on the market and are more effective 
than the hand method. 

Recently a new method of attack has been discovered which 
is said to work well where only a few gophers have to be 
dealt with. An automobile is placed over the hole and a short 
hose attacked to the exhaust, the other end being inserted 
in the gopher hole and packed with moist soil. After turning 
an extra amount of lubricating oil into the cylinders for the 
purpose of making a smoky gas, the engine is started. If 
smoke is emitted from any hole in the vicinity it is promptly 
plugged. A few minutes of this treatment naturally pro- 
duces a condition fatal to the gopher. 

Ground Squirrels (CiteUus bcecheyi) 

These animals overrun California, occurring by millions 
in the interior valleys, where they destroy large quantities 
of grain, almonds, and dried fruit. They may do great dam- 
age to citrus orchards and nurseries but, unlike the gopher, 
their depredations are largely confined to orchards situated 
near grain fields or brush land. Railroad embankments, 
canal banks, and roadsides are favorite places for squirrel 
burrows. The animals live mostly on grain, nuts, acorns, and 
weed seeds, but during the rainless summer and fall, when 
the green herbage dries up, they are apt to visit citrus trees 
and gnaw the bark. A few squirrels may quickly ruin a 
large number of trees when the young trees have just been 
planted out. 

Ground squirrels may be poisoned in the same way as 
gophers, poisoned barley or wheat being most commonly used 
for this purpose. Whole barley threshed but still retaining 
its rough outer husk will not be eaten by birds, so it should 
always be used in this form. The following formula and di- 
rections for preparing poisoned barley are suggested : 



Various Orchard Pests and their Control 459 

Whole barley 20 pounds 

Vinegar 1^ pints 

Strychnia sulfate 1 ounce 

Honey 1 pint 

Cyanide of potassium 1^ ounces 

Eggs 1 dozen 

Pulverize the strychnine in the vinegar and see that it all 
dissolves. Dissolve the cyanide in a little water. Beat the 
eggs thoroughly. Mix all the ingredients together and stir 
well before adding to the barley. Stir at intervals during 
the next few hours and dry before using as it will mold if put 
away wet. Grain coated with poison is more effective than 
grain soaked in poison for the reason that much of the grain 
being gathered, carried into the burrows and stored for 
winter use is not immediately effective. When the grains 
are coated with poison, enough will be absorbed by the cheek 
pouches during transit to produce death. 

Another very effective poison during the dry season is 
halved ripe cull oranges, upon the cut surfaces of which 
strychnine has been smeared. 



CHAPTER XXV 
BIBLIOGRAPHY 

OTHER BIBLIOGRAPHIES 

Waters, Carrie S. "Citrus Fruits and Their Culture," a Bibliog- 
raphy classified according to subjects. Published 1913 by 
San Bernardino Free Public Library. 

Ferrari, E. Extensive Bibliography of the Lemon. Bol. Abor. 
Ital. 5 (1909), pp. 145-80. 

Savastano, L., and Parrozzani, A. List of about Fifty Articles on 
Citrus in European Literature. Annals Royal Italian Ex- 
periment Station for Agr. and Fruit Culture, Vol. 1, 1911. 

Cook, A. J. "Bibliography of Citrus." In " California Citrus Cul- 
ture," Calif. State Com. Hort., 1913. 

Hume, H. H. "American Citrus Literature." In Chapter XIV, 
"Citrus Fruits and Their Culture," 1907. 

REFERENCES TO LITERATURE DEALING WITH PAR- 
TICULAR FRUITS 

Orange Growing in United States 

Craw, A. "Working Over Old Orange Trees." Pacific Rural 

Press, May 9, 1885. 
Garey, T. A. "Orange Culture in California." San Francisco, 

1882. 
Jackson, J. R. "Notes on Oranges." Garden. Copied in U. S. 

D. A. Yearbook, 1887, p. 56. 
Lummis, C. F. "Oranges 250 Years Ago." The Land of Sunshine, 

Vol. XVI, Feb., March, and April, 1902. 
461 



462 Bibliography 

Spalding, W. A. "The Orange, Its Culture in California." River- 
side, 1880. 

Skinner, L. B. "Orange Culture in Florida." Proc. Am. Pom. 
Soc. 1911, pp. 70-6. 

Whitney, J. P. "Educational Orange Growing." Sunset Maga- 
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Wallace, T. C. "The Cultivation of Oranges." Pacific Rural 
Press, Oct. 24, 1908. 

Saunders, Wm. "Notes on Orange Culture." Rpt. of U. S. 
Dept. of Agr. 1886, p. 687. 

Hart, E. H. "The Orange." The American Fruit Culturist, 1908, 
p. 621. 

Onderdonk, Gilbert. "The Orange in Texas." Texas State 
Dept. Agr. Bui. 9, p. 7. 

Manville, A. H. "Practical Orange Culture." -Jacksonville, 
Ashmead Bros., 1883. 

Powell, E. P. "The Orange, Another of our First Families." 
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Mevers, W. A. "How to Grow and Cultivate an Orange Grove 
in Louisiana." La. State Hort. Soc. Proc. 1906, p. 71. 

Brown, E. "Oranges in Northern California." Scientific Ameri- 
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[Carnes, E. K.] "Development of the Orange Industry in Cali- 
fornia." Natomas News, Vol. 3, No. 1, March, 1913. 

Horgan, H. V. "Growing Oranges under Tents." Country 
California^, Vol. 1, pp. 717-19, 750, Dec. 1905. 

Wickson, E. J. "The Orange in Northern and Central California." 
San Francisco Chronicle, Jan. 1, 1903. Reprinted by State 
Board of Trade. 

Williamson, Robert. "Orange Growing in Central and Northern 
California." Pacific Rural Press, Vol. 39, p. 2, Jan. 4, 1890. 

Kinney, A. "The Orange, History, Analyses, Varieties." Pacific 
Rural Press, March 21, 1885, p. 282. 

Guinn, J. M. "From Cattle Range to Orange Grove." Pacific 
Monthly, Oct. 1910. 



Bibliography 463 

Moremen, M. S. "Present Condition and Treatment of Orange 
Groves." Florida Agr. Exp. Sta. Bui. 33, 1896. 

Bennett, J. E. " Roofing j Over Orange Orchards." Current 
Literature, Vol. 27, pp. 146-7, Feb. 1900. 

Orange Growing in Foreign Countries 

Ferrarius, J. B. "The Hesperides or About the Golden Apples. 

' Their Culture and Use. In Four Books." Rome, 1646. 
Pye, Thomas. "History and Culture of the Orange." Dept. Agr., 

New South Wales, Bui. 1, 1890. 
Alderton, G. E. "Treatise and Handbook of Orange Culture in 

Auckland, New Zealand." Wellington, 1884. 
Moody, J. F. "The Cultivation of the Orange." Dept. of Agr., 

West Australia, Bui. 34, 1912. 
Trabut, L. V. "L'Oranger en Algerie." Direction de l'agriculture 

gouv. gen. Algerie, Bui. 44, 1908. 
Freeman, L. R, "The Orange in the West Indies." Pacific 

Rural Press, June 21, 28, and July 5, 1913. 
Bell, H. H. "Cultivation of Oranges in Dominica." Imp. Dept. 

of Agr., Barbados, Bui. 37, 1905. 
Abella, A. "Orange Culture in Montevideo." Min. Indus. 

(Uruguay) Insp. Nac. Gan. y Agr., Bol. 7 (1913), p. 48. 
[Anonymous.] "Orange Growing in Lower California." Pacific 

Rural Press, Nov. 22, 1884. 
Amoore, H. E. "Japanese Orange Growing." Pacific Rural Press, 

No. 19, 1887, p. 411. 
Orchard, P. W. "A Study of the Orange Districts of Spain." 

The Florida Grower, Oct. 11, 18, 25, 1913. 
Newcomer, E. J. "Oranges at Seville." Pacific Rural Press, 

June 7, 1913. 
Shamel, A. D. "Orange Growing in Brazil." Pacific Rural Press, 

Jan. 10, 1914, p. 41. 
Bertoni, G. T. "The Oranges of Paraguay." An. Rpt. Estacion 

Agron. de Puerto Bertoni Para 1911 y 1912, p. 195. 



464 Bibliography 

Shepstone, H. J. "Jaffa Orange Culture." World's Work 

(London), Vol. 17, pp. 199-203, Jan. 1911. 
Eisen, G. "The Jaffa Orange in Egypt." Calif. Cultivator, Jan. 

23, 1913, p. 100. 
[Anon.] "The Orange Industry of Palestine." Hacherouth, No. 20, 

1913. 
Aaronsohn, A., and Soskin, S. "The Orange Groves of Jaffa." 

Tropenpflanzer, Vol. 6. 
Aaronsohn, A. "Jaffa Oranges in Palestine." U. S. D. A. Bureau 

Plant Industry, Bui. 180, 1910, p. 25. 
[Anon.] "An Orange Farm." South African Agr. Journ., Feb. 

1913, p. 176. 
McIlwaine, R. "The Possibilities of Rhodesia as a Citrus Growing 

Country." Dept. Agr. Rhodesia, Bui. 2, Feb. 1908. 
Farmer, C. E. "Citrus Fruit Trees from Seed to Grove." Dept. 

Agr. Rhodesia, Bui. 153, Aug. 1913. 
"Citrus Fruits in Rhodesia." Dept. Agr. Rhodesia, Bui. 164, 

Dec. 1913. 
"Rhodesian Citrus Fruit." Dept. Agr. Rhodesia, Bui. 166, Dec. 

1913. 
McIlwaine, R. "Some Citrus Growing Experiences in Rhodesia." 

Dept. Agr. Rhodesia, Bui. 182, June, 1914. 

Varieties 

Chapman, C. C. "Orange Varieties and Their Respective Merits." 
Rpt. 28th Calif. Fruit Growers Convention, 1903, p. 163. 

Saunders, Wm. "Washington Navel Orange, Its History and Pollen 
Production." U. S. D. A. Yearbook, 1887, P . 640. 

Van Deman, H. E. "History of the Washington Navel Orange." 
American Garden, June, 1888, p. 231. 

Hart, E. H. "History of the Various Navel Oranges under Culti- 
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Van Deman, H. E. "The Navel Orange, Another Chapter in Its 
History." Semi-Tropical Planter, June, 1887. 



Bibliography 465 

"Bahia or Washington Navel Orange." Rpt. U. S. Dept. Agr., 

1886, p. 267. 
"History of the Washington Navel Orange." U. S. D. A. Year- 
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"History of the Introduction of the Washington Navel." Rural 

New Yorker, June, 1899. 
Coit, J. Eliot. "The History of the Washington Navel or Bahia 

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of Orange County, 1911, p. 74. 
Reasoner, P. W. "The Navel Oranges in Florida." American 

Garden, April, 1888, p. 135. 
Mills, J. W. "Origin of the Golden Nugget Navel Orange." 

Calif. State Bd. Hort. Rpt. 1902, p. 256. 
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D. A. Yearbook, 1911, p. 436. 
Hume, H. H. "The Surprise Navel Orange." Proc. 29th Am. 

Pom. Soc. 1905, p. 169. 
Earle, S. F. "The Navel Orange in Cuba." Calif. Cultivator, 

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2h 



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The Lemon 

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Cultivator, Feb. 23, 1911 and continued in subsequent numbers. 
Bernard, A. "Citrus Triptera as a Grafting Stock." Revue 

Horticole, Vol. 80, p. 140, 1908. 
Swingle, W. T. "Citrus Trifoliata in Relation to Citrus Culture." 

Proc. Am. Pom. Soc. 1911, p. 218. 
Wolf, F. A. "A Field Method for Distinguishing between Certain 

Orange Stocks." Alabama Exp. Sta. Circular 17, July, 1912. 
Wickson, E. J. "Citrus Trifoliata in California." Pacific Rural 

Press, June 20, 1907. 

Citrus Breeding 
Webber, H. J. "Complications in Citrus Hybridization caused by 
Polyembryony." Bot. Gaz. Vol. 29, 1900, p. 141. 
"New Citrus Fruit Creations of the Department of Agriculture." 

U. S. D. A. Yearbook, 1904, p. 221. 
"New Citrus and Pineapple Productions." U. S. D. A. Yearbook, 

1906, p. 329. 
"Present Status of Citrus Breeding." Proc. Am. Pom. Soe. 1907, 
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Swingle, W. T. "Some New Citrus Fruits." Am. Breeders' Mag. 
Vol. IV, No. 2, 1913. 



480 Bibliography 

Swingle, W. T. "Citrus Breeding Experiments." In article on 
Crop Improvement. U. S. U. A. Plant Ind. Circular 116, 1913. 
"Variation in First Generation Hybrids (Imperfect Dominance) : 
Its Possible Explanation through Zygotaxis." IV Confer- 
ence Internat. de Genetique, Paris, 1911, pp. 381-394. 

White, O. E. "Swingle on Variation in F 1 Citrus Hybrids and 
the Theory of Zygotaxis." Am. Nat., Vol. 48, No. 567, 1914. 

Shamel, A. D. "A Study of the Improvement of Citrus Fruits 
through Bud Selection." U. S. D. A. Plant Ind. Circular 77, 
1911. 
"A Study of Bud Selection in Citrus Fruits." Proc. 39th. Calif. 

State Fruit Growers' Convention, 1911, p. 89. 
"Breeding Citrus Fruits." Calif. State Com. Hort. Monthly Bui. 

Vol. 1, No. 9, p. 441, 1912. 
"Good and Bad Oranges and Orange Trees." Pacific Rural Press, 

June 13 and 20, 1914. 
"Bud Selection in Citrus Fruits." Pacific Rural Press, Jan. 31, 
1914. 

Vaile, R. S., and Reed, F. "Citrus Breeding Discussions." Calif. 
State Hort. Com. Monthly Bui. Vol. 1, No. 9, p. 479, 1912. 

Norton, J. H. "Variations in the Productivity of Citrus Trees." 
Calif. Cultivator, March 6, 1913. 

Wickson, E. J. "Improvement of Citrus Fruit Varieties." Am. 
Breeders' Assoc. Rpt. 1907, Vol. 3, p. 271. 

Babcock, E. B. "The Improvement of Citrus Fruits." University 
of Calif. Journal of Agr. Vol. 1, No. 7, Feb. 1914. 

Vaile, R. S. "Improvement of Citrus Stock through Bud Selec- 
tion." Pomona Calif. Journ. Econ. Bot. Vol. 1, Sept. 1911. 

Kraus, E. J. "Bud Variation in Relation to Fruit Markings." 
Oregon Crop Pest and Hort. Rpt. 1913, p. 71. 

Coit, J. E. "The Relation of Asexual or Bud Mutation to the 
Decadence of California Citrus Orchards." Proc. 37th Calif. 
State Fruit Growers' Convention, 1910, p. 32. 

Coit, J. E. "Budding Wood." Calif. Cultivator, Apr. 25, 1912. 



Bibliography 481 

Hartin, E. H. "The Ultimate Orange." Pacific Rural Press, 
Vol. 40, Aug. 16, 1890, p. 140. 

Barrett, O. W. "Natural Citrus Hybrids." Phil. Agr. Rev. Vol. 
5, No. 6, p. 334, 1912. 

Emerson, R. A. "The Possible Origin of Mutations in Somatic 
Cells." Am. Nat. Vol. 47, p. 375, 1913. 

Savastano and Parrozzani. "Some Natural Hybrids of Citrus 
Fruits." Annals Royal Italian Station of Agr. and Fruit 
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citrus literature. 

Savastano, L. "Nomadic Albinism in some Orange Trees." Annals 
Royal Italian Station Agr. and Fruit Culture, Vol. 1, 1911. 

Kerner and Oliver. "Citrus Bizzaria a Graft Hybrid." In 
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Trabut, Dr. "L'Hybridation des Citrus: Une Nouvelle Tangerine 
'La Clementine.'" Revue Horticole, 1902, p. 232. 

Andre, Ed. "Oranger Hybride de Montanbau." Revue Hor- 
ticole, 1905, p. 243. 

Citrus Soils and Root Systems 

Reed, J. H. "Penetration of Orange Tree Roots." Calif. Culti- 
vator, 14 (1900), No. 21, pp. 321-3. 
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Cultivation, and Fertilization." Pacific Rural Press, 61 (1901), 
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Lipman, C. B. "Humus Discussion, Cover Crops." Calif. Culti- 
vator, Dec. 4, 1913. 
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Hort. Monthly Bui. Vol. 3, No. 1, Jan. 1914. 
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Sta. Circular 111, 1913. 

Call, A. F. "How to Handle Citrus Soils." Calif. Cultivator, 
Feb. 5, 1914. 

Hilgard, E. W. "Acidity of the Root Sap of Citrus Trees." Calif. 
Exp. Sta. Rpt. 1895-97, pp. 181-3. 
2i 



482 Bibliography 

Hilgard, E. W. "Marly Subsoils and the Chlorosis or Yellowing 
of Citrus Trees." Calif. Exp. Sta. Circular 27, 1906. 
"Hardpan and Cultivation." Calif. Exp. Sta. Report, 1898- 
1901, p. 149. 

Chase, E. "Investigation of Citrus Subsoils." Proc. 37th Calif. 
State Fruit Growers' Convention, 1910, p. 61. 

Loughridge, R. H. "Alkali Tolerated by Oranges." Calif. Exp. 
Sta. Bui. 133, 1901, p. 17. 

Paine, C. R. "Soil Treatment in Citrus Orchards." Calif. Culti- 
vator, March 6, 1913. 

Bristol, W. M. "Sand on Heavy Citrus Soils." Calif. Culti- 
vator, March 6, 1913. 

Mills, J. W. "The Use of Dynamite in Orchard Planting." Calif. 
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Irrigation 

Loughridge, R. H. "Distribution of Water in the Soil in Furrow 
Irrigation." U. S. D. A. Office Exp. Sta. Bui. 203, 1908. 

Etchevery, B. A. "The Selection and Cost of a Small Pumping 
Plant." Calif. Exp. Sta. Circular 117, 1914. 
"Irrigation and Cultivation of Orchards." Dept. Agr. British 
Columbia, Victoria, Bui. 44, 1912. 

Wickson, E. J. "The Water Needs of Citrus Trees." U. S. D. A. 
Farmers' Bui. 116, 1900. 

Tait, C. E. "Cost of Irrigating Citrus Fruits." Pacific Rural 
Press, June 3, 1911. 
"Irrigation of Citrus Orchards." U. S. D. A. Office Expt. Sta. 
Bui. 236, 1911. 

Kritzer, W. H. "Definitions and Equivalents for Irrigation and Hy- 
draulic Computations." Pacific Rural Press, July 27, 1912, p. 28. 

Adams, F. "Irrigation Resources of California and their Utiliza- 
tion." U. S. D. A. Office Exp. Sta. Bui. 254, 1913. 

Whitney, D. J. "Overhead Irrigation in the Citrus Grove." 
Pacific Rural Press, July 13, 1912. 



Bibliography 483 

Woehlke, W. V. ' ' The Water Savers." The Outlook (New York) , 

March 25, 1910, Vol. 94, p. 659. 
Wallace, T. C. "Irrigating Oranges." Pacific Rural Press, Oct. 

31, 1908, p. 276. 
Forbes, R. H. "Irrigating Citrus Trees in Alkali Soil." Arizona 

Exp. Sta. Bui. 44, 1902, p. 171. 
Koethen, E. L. "Irrigation, the Citrus Growers' Catechism." 

Pacific Fruit World, May 20, 1911, p. 4. 
Stanley, F. M. "Irrigation of Citrus Groves." Florida Grower, 

May 17, 1913. 

Fertilization 

Hilgard, E. W. "Fertilizers for California Orange Trees." Pacific 

Rural Press, Nov. 7, 1908, p. 294. 
Webber, H. J. "Fertilization of the Soil as Affecting the Orange 

in Health and Disease." U. S. D. A. Yearbook, 1894, 

pp. 193-202. 
Colby, G. E. "Ingredients withdrawn from the Soil by Citrus 

Fruits." Exp. Sta. Record, Vol. 5, pp. 5-89. 
"Effect of Fertilizers on Fruit of Navel Oranges." Calif. Exp. 

Sta. Rpt. 1895, pp. 172-7. 
Floyd, B. F. "Problems in Citrus Nutrition." Florida Exp. Sta. 

Rpt. 1911. 
Wright, George. "Fertilizing Citrus Fruits." Calif. Cultivator, 

Oct. 30, 1913. 
Webber, H.J. "Fertilizer Experiments with Citrus Fruits." Calif. 

Cultivator, Dec. 11, 1913. 
Call, A. F. "Fertilizing California Citrus Orchards." Calif. 

Cultivator, Feb. 19, 1914, p. 228. 
Painter, E. O. "Fertilizers for Citrus Fruits." Proc. 32d Session 

Am. Pom. Soc. 1911, pp. 54-9. 
Murtado, D. J. "Fertilizing Oranges in Spain." Calif. Culti- 
vator, Dec. 4, 1913. 
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Bd. Hort. Rpt. 1888, p. 150. 



484 Bibliography 

Wallace, T. C. "Fertilizing Orange Orchards." Pacific Rural 
Press, Nov. 7, 1908. 

Blair, A. W. "Experiments on Citrus Fertilization." Florida 
Exp. Sta. Rpt. 1911. 

Wickson, E. J. "Oranges and Potash." Pacific Rural Press, 
Nov. 20, 1909, p. 323. 

Hilgard, E. W. "Effect of Citrus Culls on Soil." Calif. Culti- 
vator, June 6, 1912. 

Robertson, G. R. "Citrus Culls as a Fertilizer." Calif. Culti- 
vator, June 15, 1911, p. 208. 

Cover-Crops and Green Manuring 

Goeze, E. "Early Green Manuring of Oranges." Gardeners' 
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Davy, J. B. "Lupines for Green Manuring in California." Calif. 
Agr. Exp. Sta. Rpt. 1897-98, p. 203. 

McKee, R. "Orchard Green Manure Crops in California." U. S. 
D. A. Plant Ind. Bui. 190, 1910. 

Messenger, C. B. "Buckwheat for Humus." Calif. Cultivator, 
June 4, 1914, p. 680. 

Call, A. F. "Green Crops in the Citrus Orchard." Calif. Culti- 
vator, Feb. 12, 1914, p. 196. 

Waterbury, G. W. "Cover-Crops in Citrus Orchards." Calif. 
Cultivator, Jan. 15, 1914. 

Mertz, W. M. "Citrus Cover-Crops." Calif. Cultivator, Jan. 8, 
1914, p. 36. 

Geraldson, G. "Green Manuring." Calif. Cultivator, Oct. 5, 
1911, p. 314. 

Lipman, C. B. "Green Manuring in California." Calif. Exp. 
Sta. Circular 110, 1913. 
"The Function of Cover-Crops." Orchard and Farm (San Fran- 
cisco), Jan. 1914, p. 201. 

Adamson, J. E. " Cover-Crops for Citrus Fruit." Pacific Rural 
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Bibliography 485 

Norton, J. H. "Citrus Cover-Crops." Calif. Cultivator, Jan. 27, 

1910. 
Koethen, E. L. "The Best Citrus Cover-Crop." Pacific Fruit 

World, June 17, 1911. 
Whitney, D. J. "Advantages of Alfalfa in Orchards." Pacific 

Rural Press, Dec. 13, 1913. 
Lipman, C. B. "Citrus Cover-Crops." Proc. 39th Calif. State 

Fruit Growers' Convention, 1911, p. 124. 
Piper, C. V., and McKee, R. "Vetches." U. S. D. A. Farmers' 

Bui. 515, 1912. 

Varieties — Botany 

Swingle, W. T. "Eremocitrus, a New Genus of Hardy Drouth-Re- 
sistant Citrous Fruits from Australia." Journ. Agr. Research, 
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Swingle, W. T., and Kellerman, Maude. "Citropsis, a New 
Tropical African Genus Allied to Citrus." Journ. Agr. Re- 
search, Vol. 1, No. 5, 1914. 
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Parish, S. B. "Botanic View of the Orange." Proc. 37th Calif. 
Fruit Growers' Convention, 1910, p. 21. 

Andre, Ed. "Oranges Monstrueuses." Revue Horticole, 1900, 
p. 423. 

[Anon.] "Ringing Oranges." Scientific American, Dec. 14, 1912, 
p. 515. 

Cutter, J. E. "Varieties of Citrus Fruits." Calif. State Bd. 
Hort. Rpt. 1894, p. 250. 

Lelong, B. M. "New Varieties of Citrus Fruits." Calif. State 
Bd. Hort. 1891. 

[Anon.] "New Citrus Varieties." Pacific Rural Press, Vol. 41, 
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486 Bibliography 

Chemistry — Judging 
Colby, G. E. "Analyses of California Oranges." Calif. Exp. 
Sta. Bui. 93, p. 6, 1891. 
"Analyses of California Oranges and Lemons." Calif. Exp. Sta. 

Rpt. 1893-94, pp. 240-56. 

"Comparison of Shipping Navel Oranges from Northern, Southern, 

and Middle California." Calif. Exp. Sta. Rpt. 1898-1901, p. 244. 

"Composition of Citrus Culls." Calif. Exp. Sta. Rpt. 1898, p. 259. 

Pickell, J. M., and Earle, J. J. "Analyses of Oranges." Florida 

Exp. Sta. Bui. 17, 1892. 
Collision, S. E. "Sugar and Acid in Oranges and Grapefruit." 

Florida Exp. Sta. Bui. 115, 1913. 
Henry, A. M. "The Chemical Composition of Florida Oranges." 

Florida Dept. Agr. Quar. Bui. Vol. 23, No. 2, April, 1913. 
Rose, R. E. "Immature Citrus Fruit." An. Rpt. Florida State 
Chemist, Dec. 31, 1913. 
"Report of Commission Appointed to prepare Immature Citrus 
Fruit Standard." Florida Dept. Agr. Quar. Bui. Vol. 22, No. 4, 
Oct. 1, 1912. 
"Analyses of 280 Samples of Oranges." Florida State Chemist, 

Aug. 15, 1912. 
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lished by state printer, Florida. Not dated. 
"When is an Orange Mature and Wholesome?" Address before 
Assoc. Am. Food, Drug and Dairy Officials, Portland, Maine, 
July 16, 1914. 
"Details of the Acid Test Law in Florida." Florida Grower, 

Sept. 13, 1913. 
"Florida Green Fruit Law in Detail." Florida Grower, Aug. 23, 
1913. 
Bahadur, Rana. "Composition of Fibrous Part of Japanese 

Orange." Univ. Tokyo, Col. Agr. Bui. Vol. VII, No. 1, 1906. 
Southerst, W. F. "Sugar Content of Oranges." Calif. Culti- 
vator, May 18, 1911, p. 612. 



Bibliography 487 

Bancroft, A. L. "Where is the Orange the Sweetest?" Pacific 

Rural Press, July 8, 1911, p. 25. 
Van Deman, H. E. "Judging Citrus Fruits." Proc. Am. Pom. 

Soc. 1889, p. 145. 
Hume, H. H. "Judging Citrus Fruits." Citrus Fruits and their 

Culture, p. 155, 1903. 
"Judging Citrus Fruits." Proc. 23d Session Am. Pom. Soc. 1891, 

pp. 152-6. 
Cutter, J. E. "Scale for Judging Citrus Fruits." Calif. State 

Com. Hort. Rpt. 1889, p. 365. 
[Anon.] "Judging Citrus Fruit." Rural Californian, Dec. 1910, 

p. 364. 
Shamel, A. D. "Rules for Judging Citrus Fruits." Calif. Culti- 
vator, May 15, 1913. (See also June 5, 1913, p. 694 for judging 

trees in the orchard.) 
[Anon.] "Citrus Standard Score Card." Pacific Rural Press, Jan. 

10, 1914, p. 42. 

Pruning 

Coit, J. E. "The Pruning of Citrus Trees." Calif. Cultivator, 

Oct. 21, 1913. 
Englehardt, J. P. "The Pruning of the Washington Navel Tree." 
Proc. 37th Calif. State Fruit Growers' Convention, 1910, p. 97. 
Paine, C. R. "Pruning to Improve the Orange." Proc. 28th 
Calif. State Fruit Growers' Convention, 1903, p. 169. 
"Orange Pruning." Calif. Cultivator, Jan. 22, 1904, p. 75. 
"Renovation of the Orange Tree by Systematic Pruning." 
Proc. 37th Calif. State Fruit Growers' Convention, 1910, p. 28. 
"Pruning out the Australian Type." Calif. Cultivator, May 

16, 1912. 
"Systematic Pruning of the Orange Tree." Calif. Cultivator, 
May 16, 1912. 
Whitney, D. J. "A Change in Orange Pruning." Pacific Rural 
Press, Aug. 3, 1912. 
"Pruning Navels — Wild Wood." Pacific Rural Press, Jan. 17, 
1914. 



488 Bibliography 

Whitney, D. J. "Right Pruning and Novel Quality." Orchard 

and Farm (San Francisco), May, 1914, p. 2. 
Call, A. F. "Pruning Citrus Trees." Calif. Cultivator, Feb. 12, 

1914, p. 197. 
Salle, J. W. "Pruning Citrus Trees." Calif. State Bd. Hort. 

Rpt. 1888, p. 211. 
Little, F. A., and Rumsey, C. E. "Pruning Citrus Trees." Rural 

Californian, March, 1909, p. 84. 
Williams, E. A. "The Pruning of Citrus Trees." Rural Cali- 
fornian, March, 1910, p. 89. 
Towt, C. W. "Citrus Tree Surgery." Univ. Calif. Journ. Agric. 

Oct. 1913. 
Bristol, W. M. "Pruning the Orange." Pacific Rural Press, 

May 29, 1909. 
Wallace, T. C. "Pruning Orange Trees." Pacific Rural Press, 

Nov. 14, 1908. 
Koethen, E. L. " Propping Citrus Trees." Pacific Rural Press, 

Oct. 26, 1907. 
Stiles, H. C. "Lemon Pruning in California." American Garden, 

Jan. 1891, p. 47. 
Williams, E. A. "Hints on Pruning Orange Trees." Pacific Rural 

Press, March 12, 1910. 
Leffingwell, C. W., Jr. "Pruning the Lemon Tree." Calif. 

Cultivator, No. 13, 1900, pp. 193, 199, and 200. 
Allen, R. C. "Pruning the Lemon Tree." Pacific Rural Press, 

Vol. 60 (1900), No. 13, p. 197. 
Lewis, E. S. "Shaping Lemon Trees." Calif. Cultivator, Aug. 28, 

1913, p. 198. 
Coit, J. E. "Dressings for Wounds of Citrus Trees." Calif. Culti- 
vator, Feb. 13, 1913. 
"Pruning Frosted Citrus Trees." Calif. Exp. Sta. Cir. 100, June, 

1913. 
Hodges, R. E. "Delayed Pruning Saved Frosted Citrus Trees." 

Pacific Rural Press, July 11, 1914. 



Bibliography 489 

Curing — Storing — Sweating — Packing 
Teague, C. C. "Curing and Marketing Lemons." Proc. 28th 

Calif. State Fruit Growers' Convention, 1903, p. 63. 
Sievers, A. F. and True, R. C. "Keeping Quality of Lemons." 

Pacific Rural Press, June 19, 1909. 
"Some Factors Affecting the Keeping Qualities of American 

Lemons." U. S. D. A. Plant Ind. Cir. 26, 1909. 
"A Preliminary Study of the Forced Curing of Lemons as 

Practiced in California." U. S. D. A. Plant Ind. Bui. 232, 

1912. 
Hart, J. H. "Precooling of Perishable Freight." Engineering 

Mag., Vol. 36, pp. 288-9, 1908. 
Stubenrauch, A. V. "The Relation of Handling to Decay in 

Calif. Navel Oranges in 1910-11." U. S. D. A. Plant Ind. 

July 13, 1911. 
Call, A. F. "Sweating Citrus Fruit." Calif. Cultivator, March 5, 

1914, p. 292. 
Williams, L. B. "The Coloring of Oranges and Lemons by the 

Sweating Process." Proc. 37th Calif. State Fruit Growers' 

Convention, 1910, p. 104. 
Bigelow and Gore. "The Ripening of Oranges." Journ. Am. 

Chem. Soc. Vol. XXIX, No. 5, May, 1907. 
"Coloring Green Oranges." Ruling No. 133 U. S. Board of Food 

and Drug Inspection. 
Congar, et al. "Lemons, Picking and Curing." Pacific Rural 

Press, Jan. 2, 1886. 
[Anon.] "Packing Citrus Fruits." Pacific Rural Press, Jan. 21, 

1888, p. 43. 
[Anon.] "Rules for Grading California Oranges." Am. Pom. Soc. 

Proc. 1907, p. 109. 
Allison, L. R. W. "The Precooling Plant of the Santa Fe Rail- 
way." The Railway and Eng. News, May 11, 1912. 
Call, A. F. "Time to Pick Citrus Fruits." Calif. Cultivator, 

Feb. 19, 1914, p. 229. 



490 Bibliography 

Temple, W. C. "Preparing Citrus Fruits for Market." Proc. 

32d Session Am. Pom. Soc. 1911, pp. 77-83. 
Haizlip, W. T. "Forms for Packing-House Bookkeeping." 

Florida Grower, Oct. 18, 1913. 
Newcomer, E. J. "Methods of Handling Citrus Fruits in Seville." 

Calif. Cultivator, Nov. 6, 1913. 
Newlin, J. A. "Tests of Packing Boxes of Various Forms." U.S. 

D. A. Forest Service, Cir. 214, 1913. 
Hosford, G. W. "Cooperation in the Handling of Lemons in 

California." Cornell Countryman, Vol. 11, No. 7, 1913, p. 

209. 
Hume, H. H. "Packing Citrus Fruits." Florida Exp. Sta. Bui. 

63, 1902. 
Lelong, B. M. "Packing Oranges." Rpt. Calif. State Bd. Hort. 

1889, p. 141. 
[Anon.] "A Model Citrus Packing-House." Florida Grower, 

March 29, 1913. 
Call, A. F. "Packing Citrus Fruits." Calif. Cultivator, March 12, 

1914, p. 324. 
Stubenrauch, A. V., and Dennis, S. J. "The Precooling of Fruit." 

U. S. D. A. Yearbook, 1910. 
Works, J. D. "Details of Packing Lemons and Placing Them in 

the Cars." Speech before U. S. Senate, July 24, 1913. 

Marketing, Organization, Statistics, Tariff 
Cook, O. G. "Transportation of Citrus Fruits." Proc. Am. Pom. 

Soc. 1911, p. 98. 
Dwinelle, C. H. "Notes on Keeping Quality of California 

Oranges." Pacific Rural Press, June 14, 1884, p. 435. 
Powell, G. H. "Cooperation in the Handling and Marketing of 

Fruit." U. S. D. A. Yearbook, 1910. 
Stubenrauch, A. V., et al. "Factors Governing the Successful 

Shipment of Oranges from Florida." U. S. D. A. Bui. 63, 

March 28, 1914. 



Bibliography 491 

Call, A. F. "Marketing Citrus Fruit." Calif. Cultivator, March 

. 12, 1914. 
Coit, J. E. "Shipping Green Oranges." Calif. Cultivator, June 18, 

1914. 
"The Marketing of Frosted Citrus Fruit." Decision No. 150, 

U. S. Board of Food and Drug Inspectors. 
Works, J. D. "History of the California Fruit Growers' Exchange ; 

Its Methods and Legal Status." Speech in U. S. Senate, July 

24, 1913. 
Barrett, O. W. "The Valencia Orange Trade." Philippine Agr. 

Rev. Feb. 1913, Vol. VI, No. 2. 
[Anon.] "Prices Received for Florida Citrus Fruits Averaged by 

Seasons." Florida Grower, June 7, 1913. 
Phillips, T. H. "Methods of the California Citrus Union." 

Pacific Rural Press, Aug. 17, 1907. 
Woodford, B. A. "Organized Citrus Fruit Marketing." Proc. 

39th Calif. Fruit Growers' Convention, 1911, p. 85. 
"California Fruit Growers' Exchange and Its Relation to the 

Citrus Fruit Industry." Proc. 40th Calif. State Fruit Growers' 

Convention, 1912, p. 40. 
Powell, G. H. "Organization of the California Citrus Fruit In- 
dustry." U. S. D. A. Yearbook, 1910, p. 405. 
"California Fruit Growers' Exchange." Calif. Cultivator, March 

13, 1913. 
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Cal. State Hort. Com. Vol. 11, No. 11, Nov. 13, 1913, p. 

721. 
Whitney, D. J. "Working Methods of Citrus Cooperation." 

Orchard and Farm, May, 1914, p. 5. 
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Press, Aug. 10, 1912. 
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in Citrus Fruits and Their By-Products." Citrus Protective 

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492 Bibliography 

Tait, C. E. "The Cost of the Producing Citrus Fruits.". U. S. D. 

A. Office of Exp. Sta. Bui. 236, 1911. 
Powell, G. H. "The Cost of Producing Oranges in California." 

Citrus Protective League, 1912. 
[Anon.] "Protection for Home Grown Oranges and Lemons." 

Pac. Rural Press, Vol. 39, p. 249, March 8, 1890. 
[Anon.] "The Citrus Tariff — Brief of Facts." Citrus Protective 

League, 1908. 
Adams, S. H. "The Lemon and the Tariff." McClure's Mag. 

Vol. 36, pp. 353-60, Jan. 1911. 
[Anon.] "Tariff and Lemons." Outlook, Vol. 92, pp. 337-8, 

June 12, 1909. 
[Anon.] "Reasons Why the Tariff Should not be Removed on 

Lemons." Overland, Vol. 59, pp. 258-9, March, 1912. 

By-Products 

Chace, E. M. "Italian Lemons and Their By-Products." U. S. D. 
A. Plant Ind. Bui. 160, 1909. 

Cheney, A. S. "Citrus By-Products Manufacture in Sicily." 
U. S. Consular Rpt. 1908. 

Bioletti, F. T. "Vinegar from Orange Culls." Calif. Cultivator, 
Jan. 30, 1913. 

Cruess, W. V. "Making Orange Vinegar." Calif. Cultivator, 
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"Utilization of Waste Oranges." Calif. Exp. Sta. Bui. 244, 1914. 

Skinner, L. B. "Orange Culture in Florida." (Discussion of Juice 
Bottling), Proc. Am. Pom. Soc. 1911, p. 70. 

Stubenrauch, A. V. "Uses of Citrus Fruits." Good House- 
keeping, Vol. 54, pp. 103-8, Jan. 1912. 

[Anon.] "What Can Be Made of Orange Peel." Scientific Ameri- 
can, Vol. 84, p. 88, Feb. 9, 1901. 

[Anon.] "Canned Lemons and Lemon Juice." Pacific Rural 
Press, March 14, 1885, p. 225. 

[Anon.] "Orange Flower Cultivation in France." Gardeners' 
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[Anon.] "The Distillation of Orange Flowers at Grasse." Journ. 

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Penzig, O. "Chimica Fisiologica delle Auraneiacle." Annali di 

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Dunbar, P. B., and Bigelow, W. D. "The Acid Content of 

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Woodbridge, T. R. "Orchard Heating Costs." Pacific Rural 

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Diseases 
Smith, R. E., and Smith, E. H. "Citrus Diseases." In Calif. 

Expt. Sta. Bui. 218, June, 1911. 
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Hume, H. H. "Some Citrus Troubles." Florida Exp. Sta. Bui. 

53, 1900. 
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May 25, 1911. 
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Hort. Com. 1913. 
Cobb, N. A. "Citrus Root Nematode." Jour. Agr. Research, 

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Journ. Agr. Research, Vol. 2, No. 2, May, 1914. 



Bibliography 501 

Gile, P. L. "Relation of Calcareous Soils to Pineapple Chlorosis." 
Porto Rico Exp. Sta. Bui. 11, 1911. 

Floyd, B. F. " Frenching, Yellow Spotting, Die-Back, and Melanose 
of Citrus." Fla. Exp. Sta. Rpt. 1910. 
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1909. 

Hilgard, E. W. "Marley Subsoils and the Chlorosis or Yellowing 
of Citrus Trees." Calif. Exp. Sta. Circular 27, 1906. 

Coit, J. E. "Mottled-Leaf of Citrus not Spread by Budding." 
Calif. Cultivator, Jan. IS, 1912, p. 68. 

Snowden, R. R. "Magnesia-Lime Chlorosis of Citrus Trees." 
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Lipman, C. B. "Chlorosis of Citrus Trees and the Physical Condi- 
tion of the Soil." Calif. Cultivator, June 1, 1911. 
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dustry Circular 19, 1908. 

Stevens, H. E. "Melanose and Stem End Rot." Florida Grower, 
Nov. 1, 1913. 
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Sta. Rpt. 1912. 
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Floyd, B. F., and Stevens, H. E. "Melanose and Stem End Rot." 

Florida Exp. Sta. Bui. Ill, 1912. 
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Agrumi." Agricoltura Portici, Vol. IV, 1884. 
Grossenbacher, J. G. "Experiments on the Decay of Florida 

Oranges." U. S. D. A. Plant Ind. Circular 124, 1913. 
Hedges, F., and Tenney, L. S. "A Knot of Citrus Trees Caused by 

Sphseropsis tumefaciens." U. S. D. A. Bureau Plant Ind. 

Bui. 247, 1912. 
Stevens, H. E. "Citrus Canker." Fla. Exp. Sta. Bui. 122, 

March, 1914. 
Rolfs, Fawcett, and Floyd. "Diseases of Citrus Fruits." 

Florida Exp. Sta. Bui. 108, 1911. 
Clausen, R. E. "A New Fungus Concerned with Wither-tip of 

Varieties of Citrus Medica." Phytopathology, Vol. 2, No. 6, 

Dec. 1912. 
Rolfs, P. H. "Wither-tip and other Diseases of Citrus Trees and 

Fruits." U. S. D. A. Plant Ind. Bui. 52, 1904. 
Cook, M. T., and Horne, W. T. "Wither-tip." Cuba (Santiago 

de Los Vegas) Bui. 9, 1908. 
Smith, R. E. "Wither-tip." Calif. Cultivator, July 27, 1911. 
Essig, E. O. "Wither-tip and Its Treatment." Calif. Cultivator, 

May 25, 1911. 
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1911. 
Rolfs, P. H. "Fall Dropping of Citrus Fruits." Fla. Exp. Sta. 

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9, 1908. 
Floyd, B. F. "Experiments on Die-Back of Citrus." Fla. Exp. 

Sta. Rpt. 1909. 
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Coit, J. E. "Blemishes of Citrus Fruits." Proc. 39th Calif. 

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Observations on Squamosis and Exanthema of Citrus." 

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INDEX 



Abrasions, how caused, 278. 

Absentee ownership, 356. 

Acid, contained in fruit, 63 ; sul- 
furic for fumigation, 439 ; loss of 
in respiration, 287. 

Acreage, citrus, in California by 
counties, 22 ; in California in- 
creasing, 354. 

Advertising, division of Exchange, 
350, 351. 

Agents, bonded salesmen of Ex- 
change, 348. 

Air, importance of in soil, 165. 

Alfalfa, as interculture crop, 159 ; 
as a mulch, 173 ; as cover-crop, 
182. 

Alignment, of fruit in box, 138. 

Alternaria, affecting stored lemons, 
382. 

Alternaria citri, causing fruit decay, 
388. 

Ammonia compounds, prejudicial 
to citrus trees, 372 ; as a cause 
of mottled-leaf, 379. 

Analyses of soils, 175. 

Antiquity of citrus fruits, use in 
Hebrew ceremonies, 40. 

Aphids, 427. 

Aphis gossypii, 427. 

Aramigus fulleri, 429. 

Arizona, citrus production in, 23. 

Armillaria mellea, 145, 373. 

Artesian wells, for irrigating, 192. 

Artificial coloring, by sweating, 
284 ; federal legislation regard- 
ing, 285. 



Asher, J. M., 20. 

Asphaltum, paint for wounds, 227 ; 
in fuel oil, 260 ; for wash tanks, 
386. 

Aspidiotus hederae, 420. 

Aspidiotus rapax, 420. 

Assessments, for expenses of Ex- 
change, 348. 

Associations, 345 ; affiliated with 
Exchange, 301 ; first organized, 
8; organization of, 351. 

Atmometer, records at Whittier 
and Riverside, 189. 

Atmospheric humidity, effect on 
citrus trees and fruit, 34. 

Aurantium, derivation of word, 41. 

Australia, frost in, 25 ; introduc- 
tion of Navel orange, 15; ship- 
ping oranges to, 344 ; source of 
cottony cushion scale, 6. 

Australian Navel orange, introduc- 
tion of, 16. 

Australian type, 128. 

Automatic weighing, of individual 
grades, 292. 

Automobile, used in killing gophers, 
458. 

Azores, 15, 70. 

Backus, W. H., 58. 

Bacteria, in soil, 165. 

Bacterium citriputeale, 401. 

Bags, for picking, 280. 

Bahia, Brazil, birthplace of Navel 

orange, 13. 
Balling, nursery stock, 104. 



505 



506 



Index 



Bare rooted, trees for planting, 157. 

Bark, effect of Botrytis vulgaris on, 
366 ; gnawed by squirrels, 458 ; 
new growth of, chlorophyll in, 
49 ; of sour orange resistant to 
gum-disease, 366. 

Barnyard manure, cost of, 361. 

Barometer, indicating frost, 237. 

Baronio system of pruning, 214. 

Bench-roots, 89. 

Bergamot oil, imported, 332 ; tariff 
on, 9. 

Beveling machines, 293. 

Bibliography, general, 461. 

Bigelow, W. D., 288. 

Bioletti, F. T., quoted, 240. 

Bisulfide of carbon, for killing 
gophers, 457. 

Biting insects, 405. 

Bitter orange, origin of, introduc- 
tion into Florida, 41. 

Black leaf extract, as a spray for 
thrips, 427. 

Black pit of lemon, 401. 

Black rot of Navel, 388. 

Black scale, general discussion of, 
405. 

Black smut, 290. 

Blasting, to facilitate irrigation, 
203 ; hard soil, 156 ; to ame- 
liorate soil, 146. 

Blemishes, importance in judging, 
134; of fruit, 318. 

Blizzards, 237. 

Blue mold, 387. 

Bluestone, as a disinfectant, 385. 

Bolting split limbs, 229. 

Bolton, J. P., 252. 

Bonavia, E., 60. 

Boosting plants, 193. 

Bordeaux mixture, for seed-bed 
gumming, 89, 369 ; for wither- 
tip, 381 ; for damp-off, 392. 

Bordeaux paste, for gum-disease, 
366 ; for pruning wounds, 228. 

Botany of citrus, bibliography, 485. 



Botrytis vulgaris, causing gum- 
disease, 366 ; causing fruit decay, 
388. 

Box, dimensions of lemon box, 310 ; 
material, kind of, 293 ; cost of, 
293 ; shooks, 292. 

Boxes, machines for making, 293 ; 
materials for, 292 ; size, 293. 

Breeding, references to literature, 
479 ; for frost resistance, 244. 

Brehm, 14. 

Brokerage charges, compared with 
Exchange costs, 351. 

Brown rot fruit decay, 386. 

Brown rot fungus, transmission by 
rain, 281 ; regions most seriously 
affected, 282. 

Brown rot gum-disease, 364. 

Brown spot, of Navel orange, 326 ; 
description of, 389. 

Bruises, 321. 

Brushing, removal of dust by dry 
brushing, with water, 291. 

Buckwheat, as cover-crop, 182. 

Budding, time of, 95 ; nursery stock, 
92; method of, 95; high bud- 
ding on sour-stock, 97 ; dormant 
buds, 98 ; cost, 99. 

Bud-sports, 120; how pruned, 211. 

Bud variation, 118. 

Bud-wood, selection of, 93, 128. 

Burr clover, as cover-crop, 182. 

By-product industry, needed in 
California, 354. 

By-products, references to litera- 
ture, 492 ; importation of, 331. 

California Fruit Growers' Exchange, 
history and organization of, 345. 

California Navel Orange, chemical 
analysis of, 62. 

California pruning saw, 225. * 

Canada field peas, as cover-crop, 182. 

Canker, description of, 392. 

Capital, estimating amount needed, 
360 ; of Exchange, 348. 



Index 



507 



Capital required, 358. 

Capitalization, 356. 

Carbon bisulfide, for killing gophers, 
457. 

Carbon dioxide, loss of from fruit, 
61. 

Car-load, number of boxes con- 
tained, 310. 

Cars, standard, 295 ; other than 
standard, 275 ; air spaces in, 296 ; 
bracing of boxes in, 296; freight 
on, 297 ; icing charges, 297. 

"Car Squeeze," 296. 

Cement dust, on fruit, 324. 

Central exchange, 348. 

Ceratitis capitata, 109. 

Chambers of Commerce, influence 
of, 11. 

Chapman, A. B., 16. 

Chapman, C. C, 71. 

Characters, segregation of, 120. 

Chemical Analyses of California 
Oranges and Lemons, 62. 

Chemical fertilizer, cost of, 361. 

Chemistry, references to literature, 
486. 

Chemistry of citrus fruits, 61. 

Chenopodium, as a cover-crop, 183. 

Chimeras, 120. 

Chinese lemon, as a root-stock, 154. 

Choice, grade, 292. 

Chrysomphalus aurantii, 411; var. 
citrinus, 414. 

Citellus beecheyi, 458. 

Citranges, 79. 

Citrate of lime, imported, 332 ; 
tariff on, 9. 

Citric acid, imported, 332 ; manu- 
facture of, 333 ; tariff on, 9. 

Citricola scale, discussion of, 419. 

Citron, preparation of, 337 ; bibliog- 
raphy, 473 ; grown in California, 
susceptibility to frost, variety Cor- 
sica, 80 ; imported, 332 ; introduc- 
tion into Italy, 41 ; susceptibility 
to frost, 242 ; tariff on, 9. 



Citrus areas of California, southern 
coast, interior valleys, northern 
coast, 26. 

Citrus aurantifolia, 43, 45. 

Citrus aurantium, 43. 

Citrus bergamia, 43. 

Citrus bibliography, 473. 

Citrus canker, description of, 392. 

Citrus decumana, 43, 44. 

Citrus japonica, 43, 44. 

Citrus limonia, 43, 45. 

Citrus mealy bug, 421. 

Citrus medica, 43, 45. 

Citrus nobilis, 43. 

Citrus Protective League, 353. 

Citrus sinensis, 43. 

Citrus species in North and South 
America, 42. 

Citrus trifoliata, 43. 

Cladosporium citri, 395 ; herbarum 
var. citricolum, 395. 

Classification, 42. 

Clausen, R. E., cited, 381. 

Clearing land, cost of, 359. 

Cleats, proper position of, 138. 

Climate, interior valleys, 30 ; north- 
ern coast, 31 ; southern coast 
division, 28. 

Clipper cuts, 321. 

Clippers, abrasions caused by, 278. 

Clouds, as affecting frost, 235. 

Cobb, N. A., cited, 449. 

Coccus hesperidum, 418. 

Colby, G. E., 288. 

Cold periods, historical, 230. 

College of Agriculture, service of, 
358. 

Colletotrichum glceosporioides, 380. 

Collins, J. F., cited, 228. 

Color, importance in judging, 136. 

Coloring process, results of too 
rapid forcing, 290. 

Combustion, in orchard heaters, 
253. 

Commission men, 344. 

Concrete irrigating pipe, 194. 



508 



Index 



Conduction, 233. 

Consumption, increase of, 354. 

Contour, planting, 150. 

Convection, 233. 

Cooperation, first tried, 8 ; in frost 
fighting, 274. 

Cooperative packing-houses, 345. 

Copley, Edward, 252. 

Coquillett, D. W., 431. 

Core rot, of stored lemons, 382. 

Correspondence course, in citrus 
fruits, 358, 11. 

Cost of production, 355. 

Costs, of bringing orchard into bear- 
ing, 359. 

Cotton Exposition, held in New 
Orleans, 6. 

Cottony cushion scale, discussion 
of, 417 ; fumigation for, 431 ; in- 
troduced, 6. 

Cottony mold,; 383. 

Cottony-mold fungus, on vetch 
cover-crop, 182. 

County Commissioners of Horti- 
culture, 110. 

Cover-crop, advantages of, 181 ; 
disadvantages of, 182 ; kinds, 
182 ; references to literature, 484 ; 
harbors cottony mold, 383 ; 
plowed under, 166 ; relation to 
mottled-leaf, 379. 

Cover, T. D., first exhibited Navel 
orange, 18. 

Cowpeas, as cover-crop, 182. 

Cracks, in oranges, 326. 

Craw, Alexander, 20. 

Creosote, 227. 

Cross-furrowing, for irrigation, 201. 

Cross-pollination, 123, 115, 116. 

Crown gall, occurs on citrus, 
401. 

Cucumber beetle, 430. 

Culls, removal of, 315. 

Cultivation, 165 ; depth of, fre- 
quency of, 168. 

Cultivator scars, on fruit, 321. 



Curing, advantages of, 278 ; refer- 
ences to literature, 489. 
Cuttings, propagation by, 92. 
Cyanide, 438. . 

Damp-off fungus, in seed-bed, 88. 
Damping off, of seed-bed stock, 391. 
De CandoUe, 40. 
Decay, in pruning wounds, 226 ; 

in transit, effect of icing on, 297 ; 

in oranges, causes of, 277 ; in 

dropped fruit, 279 ; in stored 

lemons, 308 ; splits a cause of, 

327. 
Defoliation, by frost, 242. 
Degenerate types of trees, 357. 
Degeneration of trees, due to 

suckers, 209. 
Demonstration trains, influence of, 

11. 
Desiccating winds, cause of twig 

gumming, 367. 
Dew, as affecting frosts, 235. 
Dew point, raising of, 246. 
Diabrotica soror, 430. 
Die-back, see exanthema, 369. 
Digging holes, for trees, 155. 
Dimorphic branches, of orange 

trees, 208. 
Diplodia rot, due to Diplodia 

natalensis, 397. 
Discount, in cars other than stand- 
ard, 295. 
Diseases, prevention important, 

357 ; bibliography, 499 ; control, 

364. 
Disinfection, of wash water, 385. 
Distance apart, of trees, 149. 
Distillate oil, as a spray for scale, 

432. 
Distributing costs, 352. 
Distribution, of fruit by Exchange, 

348. 
District exchange, 347. 
Diversion of cars, right of, 298. 
Domestic recipes, 341. 



Index 



509 



Dosage for fumigation, calculating, 

441, 444 ; schedules, 444-447. 
Double clipping, 279. 
Dressings for wounds, 227. 
Dropped fruit, decay of, 279. 
Dry center, of lemons, 329. 
Drying, of fruit, 291. 
Dynamite, 146. 

Early ripening, of oranges in 
Northern California, 288. 

Early shipments, losses in, 283. 

Electric orchard heaters, 250. 

Electric railways, influence of, 10. 

Elevation, effect of in Interior 
Valley, 30. 

Elm, affected by mottled-leaf, 376. 

Employees, provision for, 316. 

Englehardt, J. P., 69. 

Enzymatic fermentation, of fruit, 
61. 

Eriophyes oleivorus, 424. 

Erodium, as cover-crop, 183. 

Essence of orange flowers, 338. 

Essential oils, manufacture of, 334. 

Etrog, 40. 

Eucalyptus, affected by mottled- 
leaf, 376. 

Eureka lemon, pollination of, 55 ; 
chemical analysis of, 62 ; how 
pruned, 214. 

Euthrips citri, 425. 

Evaporation, as affecting tempera- 
ture, 233 ; from porous cup 
atmometers, 189 ; from soil, 165. 

Ever-sporting trees, 211. 

Exanthema, causing blemishes on 
fruit, 325 ; description of, 369. 

Exchange, relation to other selling 
agencies, 345 ; cost of operating, 
351 ; Southern California Fruit 
Exchange first organized, 8. 

Exhibitions, judging fruit at, 132 ; 
influence of, 12. 

Explosions, in orchard heaters, 
255. 



Fairs, first citrus fairs, 5. 

Fancy, grade, 292. 

Fawcett, H. S., cited, 397. 

Feature exhibits, judging, 138. 

Federal Board of Food and Drugs 
Inspection, ruling regarding col- 
oring of green citrus fruits, 285 ; 
effect of ruling regarding artificial 
coloring, 285. 

Fenugreek, as cover-crop, 182. 

Ferrarius, John Baptiste, 13. 

Fertilization, of seed-bed, 88 ; bib- 
liography, 483 ; of nursery stock, 
92; of orchards, 175; a type of, 
178. 

Fertilizer, in planting holes, 157 ; 
cost of, 359. 

Field box, ratio of to packed box, 
295. 

Filaree, as cover-crop, 182. 

Fingered lemons, 120. 

Flavor, importance in judging, 136. 

Florida Citrus Exchange, organiza- 
tion of, 353. 

Flowers of citrus, description, 
season, 52 ; of lemon, different 
kinds of, 54. 

Fluctuations, 118, 128. 

Foot-rot, 372. 

Form, importance in judging, 133. 

Fortunella, 43. 

Freezing in transit, prevention of, 
298. 

Freight, cost of, 360. 

Freight rate, on lemons, 312. 

Freight rates, 297. 

Friendly fungi, 396. 

Frost, effect on fruit on lower 
branches, 281 ; in countries pro- 
ducing citrus fruits, 25 ; hazard, 
33 ; air currents, 34 ; effect on 
value of land, 140 ; where to be 
expected, 140; of January, 1913, 
231; losses from, 232; factors 
influencing, 234 ; local conditions 
affecting, 236 ; relative resist- 



510 



Index 



ance to, 242 ; causing blemishes 
on fruit, 325 ; a frequent cause 
of failure, 357. 

Frost fighting, bibliography, 494. 

Frost hazard, judgment of, 141. 

Frost-injured fruit, references to 
literature, 494. 

Frost injury, to vegetable tissues, 
239 ; on leaves, 368 ; prevention 
of, 243. 

Frost protection, average cost of, 
361. 

Frosted fruit, separation of, 270. 

Frosted trees, how pruned, 217. 

Frosts, as affected by winds, 233 ; 
in Florida, 230 ; in California, 
231 ; season of in California, 232 ; 
forecasting, 233. 

Froude, Charles, 252. 

Frozen fruit, changes in, 241 ; 
edible, 241 ; loss of juice, 241. 

Fruit Growers' Supply Co., organi- 
zation, 301 ; purpose, 301 ; ac- 
complishments, 301. 

Fuel oils, properties of, 260 ; stor- 
age of, 262. 

Fuller's rose beetle, 429. 

Fumigating, machine, 452 ; cost of 
materials, 452 ; cost of, 361 ; 
done by associations, 347 ; large 
seedlings difficult to cover with 
tents, 65. 

Fumigation, 431 ; season of, 443 ; 
operation, 440 ; cost of, 448 ; 
efficiency of, 403 ; bibliography, 
497; scars, 322. 

Fumigator's supply carts, 438. 

Furrows, for irrigation, 201. 

Fusarium, causing damp-off, 391. 

Galloway, B. T., quoted, 239. 
Galls, on citrus trees, 401. 
Garey, T. A., 4, 71, 74; introduc- 
tion of varieties, 16. 
Generators, fumigation, 437. 
Geomys bursarius, 456. 



Germ-plasm, 211. 

Glaced kumquats, 341. 

Glceosporium limetticolum, 381. 

Gopher, 456. 

Gore, H. C, 288. 

Grades, of fruit, 292. 

Grading, fruit, 292 ; land, cost of, 
359. - . 

Grafting, nursery stock, 92. 

Grape fruit, see pomelo, 75. 

Gravity frost, 237. 

Gray mold, of fruit, 388. 

Gray scale, 419. 

Greedy scale, 420. 

Green manure crops, 181. 

Green manuring, references to litera- 
ture, 484. 

Green mold, 387. 

Ground squirrels, 458. 

Growth rings, in wood of lemon, 
47. 

Guaymas, citrus industry at, 24. 

Gum-disease, of seed-bed stock, 89, 
368 ; in pruning wounds, 229 ; 
caused by tillage implements, 
172 ; carried by shoes of pickers, 
280. 

Gum-diseases, 364. 

Gum, formation along cambium, 49. 

Gumming, resistance of sour stock 
to, 152. 

Hail scars, 323. 

Hairy vetch, as cover-crop, 182. 

Hammon, W. H., cited, 235. 

Hardpan, 143 ; presence of, in In- 
terior Valley, 31 ; as affecting 
irrigation, 203. 

Harrowing, 168. 

Hart, E. H., 71. 

Harvest season, of oranges, of 
lemons, 63. 

Hauling fruit, average cost of, 360. 

Heading back, nursery trees, 100. 

Heading trees, 205. 

Heat, loss of, 233. 



Index 



511 



Hedges, Florence, cited, 401. 

Hemispherical scale, 420. 

Hermosillo, citrus planting at, 24. 

Hesperides, The, 13. 

Hesperidin, 241. 

Hexagonal planting, 148. 

Hilgard, E. W., quoted, 196, 431. 

Hodges, J. R., cited, 378, 449. 

Hoeing, under trees, 172. 

Holes, for tree planting, 155. 

Holt, L. M., 18. 

Honey-dew, 407 ; excreted by 
mealy bug, 421. 

Hongkong, shipping oranges to, 344. 

Horticultural inspection, cost of, 
111. 

Hume, H. H., 76. 

Humidity, for stored lemons, 308. 

Humus, produced by mulch, 173 ; 
general discussion of, 178 ; lack 
of, a cause of mottled-leaf, 378. 

Hybridization, 115. 

Hybridizing, facility of between 
species, 42. 

Hybrids, production of, distribu- 
tion of, 79. 

Hydrocyanic acid gas, first used in 
fumigation, 431. 

Icerya purchasi, description of, 
417 ; introduced, 6. 

Icing charges, 297. 

Icing of cars, effect of precooling 
on, 298. 

Icing, of lemons in transit, 312. 

Ikeda, T., 56. 

Immature fruit, sweating of, 282 ; 
shipment of, 283 ; losses in ship- 
ments of, 283 ; Florida law on, 
283 ; acid test for, 284. 

Improvement through bud selec- 
tion, 115. 

Independent shippers, 345. 

Infection, by spores, 277. 

Injuries, to fruit in packing, 322. 

Insect pests, bibliography, 496. 



Insects and control, 403. 

Inspection, horticultural, 6. 

Insurance, division of Exchange, 
350. 

Intercropping, 159. 

Interstate Commerce Commission, 
re-icing rate of, 298. 

Investment, in citrus properties, 
359. 

Irrigating system, cost of, 359. 

Irrigation, 179 ; as frost protection, 
247 ; overhead, 199 ; by basins, 
200; by furrows, 201 ; depth of, 
195 ; frequency of, 195 ; cli- 
matic conditions affecting, 188 ; 
of newly planted trees, 158 ; of 
nursery stock, 91 ; of seed-bed, 
87 ; bibliography, 482. 

Itinerant packers, 344. 

Jacobs, Louis, 21. 

Japan, frost in, 25. 

Japanese privet, affected by 

mottled-leaf, 376. 
Jelly, orange and lemon, 341. 
Jobber, 353. 
Jones, B. R., 449. 
Judging orchards and land, 363; 

references to literature, 486. 
Juice, importance in judging, 134. 

Katydids, 430. 

Keeping qualities, effect of careful 
picking, handling and packing 
on, 297. 

Kellerman and Wright, cited, 379. 

Kerosene emulsion, formula for 
black scale, 410. 

Knots on limbs, 401. 

Koebele, Albert, 6. 

Kumquat, 43, 44; bibliography, 
472 ; description of, varieties, 
Marumi, Nagami, 83 ; suscepti- 
bility to frost, 242 ; glaced, 341. 

Labeling, of boxes, 293 ; "Sunkist" 
label, 292. 



512 



Index 



Labor, cost of, 360. 

Ladders, picking, 280. 

Ladybird beetle, 417 ; for cottony 
scale, 7. 

Land, judging, 363 ; cost of, 359 ; 
stony land, development of, 145 ; 
clearing and leveling, 145. 

Lath house, for seed-bed, 86 ; as 
protection from frost, 244. 

Lavanja de Umbigo, 13. 

Layering, propagation by, 92. 

Leaf-gumming, 368. 

Leaves, season of fall, 49 ; age of, 
49 ; variation in size and shape, 
49 ; oil glands in, 50. 

Lefferts, D. C, 272. 

Legal division of Exchange, 350. 

Lelong, cited, 13, 11 ; quoted, 33. 

Lemon, black pit of, 401 ; jelly, 
341 ; peel imported, 332 ; grades, 
309 ; storage, 306 ; buttons 
dropping, 306 ; sweating, 305 ; 
picking rings, 305 ; pools, 303 ; 
susceptibility to frost, 242 ; as a 
root-stock, 154 ; length of period 
of development, 54 ; introduction 
into Italy, 41 ; bibliography, 469. 

Lemon oil, imported, 332 ; tariff 
on, 9. 

Lemon peel, tariff on, 9. 

Lemons, core rot of, 382 ; cost of 
producing, 355 ; picking, 302 
separating frosted fruit, 273 
varieties, descriptions of Eureka 
73 ; Lisbon, 74 ; Villafranca, 74 
Bonnie Brae, 75 ; Genoa, 75 
Sicily, 75 ; Messina, 75 ; Milan, 
75 ; tariff on, 9 ; standards, for 
judging, 135 ; sweet, description 
of, 83. 

Lepidosaphes beckii, 414. 

Level, for laying off contours, 151. 

Leveling land, 145. 

Lime (agricultural), 144; as a 
cure for mottled-leaf, 377. 

Lime (tree), bibliography, 471 ; 



susceptibility to frost, 242 ; tariff 
on, 9 ; description of, suscepti- 
bility to frost, varieties, sour, 
West Indian, Rangpur, Sweet, 
Mexican, 81 ; juice, preparation 
of, 339 ; imported, 332 ; oil, im- 
ported, 332. 

Lime-magnesia ratio, 377. 

Lipman, C. B., cited, 379. 

Lisbon lemon, pollination of, 55, 

Litigation, handled by Exchange, 
348. 

Local Exchange, 346. 

Location, for grove, 357. 

Longevity of citrus trees, 64. 

Los Angeles, headquarters of Ex- 
change, 346. 

Loughridge, R. H., quoted, 196. 

Lug-boxes, as carriers of infection, 
385 ; fumigating for scale, 409. 

McAdie, A. G., cited, 237. 
Magnesia, effect on mottled-leaf, 

377. 
Maintenance and repairs, average 

cost of, 361. 
Mal-di-gomma, 372. 
Malformation, of fruit, 326. 
Malforms and monstrosities, 120. 
Malnutrition, 371. 
Malva, as cover-crop, 183. 
Mandarin oranges, bibliography, 

471, 
Mandarins, varieties, description 

of tangerine, 78 ; Satsuma, 79 ; 

Unshiu, 79; Dancy, 78; King, 

78; Beauty, 78; Mikado, 78; 

Oneco, 78. 
Manifest cord, 296. 
Maple, affected by mottled-leaf, 

376. 
Marketing, 344 ; bibliography, 490 ; 

disaster of 1892-93, 7. 
Marmalades, 342. 
Marsh, C. M., 76. 
Marsh pomelo, pollination of, 55. 



Index 



513 



Mealy bug, discussion of, 421. 
Mediterranean fruit fly, quarantine 

against, 109. 
Melanose, 394. 
Meliola camellise, 290, 407. 
Melon aphis, 427. 
Membership, in Exchange, 349 ; 

in Association, 357. 
Mesembryanthemum, 150. 
Mexico, citrus industry of, 24. 
Miller, Frank A., 22. 
Miner's inch, 191. 
Mission orchards, distribution from, 

2. 
Moisture content, of soils, 196. 
Money, remitted by salesmen of 

Exchange, 350. 
Mononchus papillatus, 454. 
Monstrosities, 120. 
Morelos orange worm, 24. 
Morse, F. W., 431. 
Mother trees, for bud-wood, 94. 
Mottled-leaf, description of, 374 ; 

causing blemishes on fruit, 325 ; 

relation to nematodes, 449. 
Mulching, 173. 
Mules, as work stock, 174. 
Mussey, D. N., 303. 
Mutations, 120, 211. 
Mutual protection, division of Ex- 
change, 350. 

Nail-head rust, 395. 
Nailing, proper method, 138. 
National. Orange Show, 132. 
Navel, importance in judging, 134. 
Needham, J. H., quoted, 74. 
Nematodes, discovered on citrus, 

378 ; on citrus roots, 449 ; life 

history described, 454. 
Neroli, imported, 332 ; tariff on, 9 ; 

manufacture of, 338. 
Newland, Victor, 355. 
Nitrification in soil, 379. 
Nitrogen, as a crop limiter, 177; 

from atmosphere, 165. 

2L 



North, Judge, founded Riverside, 
17. 

Northern California, early ripening 
in, 288. 

Northers, as affecting frosts, 238. 

Norton, J. H., quoted, 124. 

Novius cardinalis, 7. 

Nursery stock, 84 ; packing for 
shipment, 102 ; cultivation, irri- 
gation, 102 ; fertilization, 102 ; 
balling, 103 ; naked roots, 102. 

Nutrition, derangement of, 374. 

Oak trees, hosts for Armillaria 
mellea, 373. 

Off-bloom, 325. 

Oil, as a fuel for orchard heating, 
252 ; of anise, used in gopher 
poison, 457 ; of bergamot, im- 
ported, 332 ; of lemon, imported, 
332 ; of lime, imported, 332 ; of 
neroli, imported, 332. 

Old age decay, of stored lemons, 
382. 

Oleander scale, 420. 

Ontario Fruit Grower, cited, 20. 

Orange, tortrix, 428. 

Orange, jelly, 341; paste, 340; 
marmalade, 342 ; wine, 337 ; 
juice, unfermented, 335 ; vine- 
gar, 336 ; peel imported, 332 ; 
susceptibility to frost, 242 ; cause 
of navel in, 61 ; pollination ex- 
periments with, 56 ; derivation 
of word, 41 ; time required in 
transit, 298 ; shipping under ice, 
298 ; number of fruits per box, 
195 ; boxes per car, 295 ; arrange- 
ment of boxes in car, 295 ; sweat- 
ing of, 282 ; thinning of fruit, 
282 ; picking to size, 282 ; decays, 
277 ; respiration of, 277 ; wrap- 
pers, cost of, 355 ; varieties, 
bibliography, 464 ; oil, imported, 
332 ; tariff on oil, 9. 

Orange diseases, bibliography, 468. 



►14 



Index 



Orange growing abroad, bibliog- 
raphy, 463. 

Orange growing in United States, 
bibliography, 461. 

Orange insects, bibliography, 467. 

Orange peel, tariff on, 9. 

Orange standards, for judging, 
133. 

Oranges and lemons of India, 60. 

Oranges, cost of producing, 355. 

Oranges crystallized, 340. 

Oranges, grades of, 292 ; tariff on, 
9. 

Oranges, varieties of, Valencia, 70 ; 
Excelsior, 70 ; Hart's Late, 71 ; 
Hart's Tardiff, 71 ; Valencia Late, 
70; Mediterranean Sweet, 71; 
Paper Rind, St. Michael, 72; 
Ruby, 72; Ruby Blood, 72; 
Jaffa, 72; Joppa, 72; Grafton, 
72 ; Asher's Best, 66 ; Bostram's 
Prize, 66 ; Washington Navel, 
66 ; Bahia, 66 ; Riverside Navel, 
66 ; Thomson, 68 ; Buckeye, 69 ; 
Navelencia, 69 ; Nugget, 69 ; 
Australian, 69. 

Orchard heaters, requirements of, 
253 ; leakage of, 255 ; types of, 
257 ; installation of, 259 ; care of, 
267. 

Orchard heating, 230 ; cost of, 268 ; 
as insurance, 33. 

Orchard heating operations, 264. 

Orchard plans, 147; tractors, 174. 

Orchards, judging, 362. 

Organization, references to litera- 
ture, 490. 

Origin of citrus fruits, 25. 

Over-capitalization, 356. 

Overhead irrigation, as a protection 
from frost, 199, 247. 

Overholtzer, David, 199. 

Packed box standards, for judging, 

137. 
Packers, 293. 



Packing, references to literature, 
489 ; process of, 295 ; speed in, 
295 ; number of fruits in a box, 
295 ; ratio of field to packed box, 
295 ; average cost of, 360 ; 
lemons, 309. 

Packing-houses, for lemons, 314; 
arrangement, 299 ; fire hazard in, 
301 ; losses from fire, 301 ; insur- 
ance for, 201 ; number of, in Cal- 
ifornia, 301 ; capacity of, 301 ; 
designing and construction of, 
299. 

Palestine, source of Jaffa orange, 
72 ; frost in, 25. 

Parsons' Navel orange, 15. 

Parsons, S. B., 70, 15. 

Parthenocarpic fruits, 55. 

Pedigreed stock, 130. 

Penicillium italicum and P. digi- 
tatum, causing fruit decays, 387. 

Performance of individual trees, 
125. 

Performance records, 128. 

Permanganate of potash, use as dis- 
infectant, 291. 

Pests, other than insects, 449 ; dis- 
tribution of, 404 ; financial loss 
caused by, 403 ; inspection and 
quarantine, 107 ; 145. 

Peteca, causing blemishes, 329. 

Petit grain oil, preparation of, 338. 

Phoma, 393. 

Phomopsis citri, 394. 

Phosphoric acid, as a crop limiter, 
177. 

Phyllosticta, 393. 

Physiological derangements, 374. 

Pickers, competition between, 317; 
payment of, 282. 

Picking, done by associations, 347 ; 
average cost of, 360 ; lemons, 
316 ; ladders for, 280 ; oranges to 
size, 282 ; oranges, care in, 277 ; 
bags for, 280. 

Picking bags, 280. 



Index 



515 



Picking lemons, 303. 

Picking season, orange, 277. 

Pipe lines, for fuel oils, 263 ; for 
water, 193. 

Placing of fruit in boxes, 13S. 

Plant-food,* amount in citrus culls, 
177 ; effect of bacteria on, 165. 

Planting, cost of, 359, 160 ; balled 
stock versus bare root, 157 ; 
depth of, 156; time of, 151; 
selection of site, 139 ; seed-bed 
stock, 91; 147. 

Planting-board, use of, 156. 

Planting plans, 147. 

Planting seed, 87. 

Plant lice, 427. 

Plowing, 165 ; depth of, 166 ; time 
of, 166. 

Plows, kinds of, 166, 170. 

Plow-sole, 166 ; as affecting irriga- 
tion, 203. 

Pocket gopher, 456. 

Poison, for gophers, 457 ; for 
ground squirrels, 459. 

Poiteau, 40. 

Pollination, 123 ; in citrus fruits of 
Florida, 55 ; in citrus fruits of 
Southwest, 45. 

Polyembryony, in hybrids, in 
citrus seeds, causes of, sig- 
nificance of, 59. 

Pomelo, subject to canker, 392 ; 
susceptibility to frost, 242 ; as a 
rootstock, 152 ; improvement by 
hybridization, 118; bibliography, 
472; picking, 312; tariff on, 9; 
standards for judging, 136. 

Pomelos, varieties, description of 
Marsh, 75 ; Nectar, 77 ; Duarte 
Seedling, 77 ; Duncan, 77 ; 
Triumph, 77 ; Imperial, 77 ; 
Colton, 77 ; Pink-fleshed, 77. 
Potash, as a crop limiter, 177. 
Potassium cyanide, for fumigation, 

449. 
Powell, G. H., quoted, 353, 346. 



Precooling, value to citrus fruits, 
298; definition of, 297; com- 
parison with icing, 297 ; amounts 
of ice required, 298. 

Precooling plants, 297. 

Prickly ash, 42. 

Privet, Japanese, affected by 
mottled-leaf, 376. 

Production, 114, 25; in California, 
9. 

Profit and loss, 355. 

Propagation, 92 ; references to 
literature, 478. . 

Propping trees, cost of, 361. 

Protective duties, tariff, 9. 

Protective League, 353. 

Pruning, as a prevention of brown- 
rot, 387 ; orange trees, 207 ; cost 
of, 359 ; done by associations, 
347 ; frosted trees, 217 ; time of, 
216; maxims of, 215; lemons, 
213 ; training nursery trees, 205 ; 
general considerations, objects 
of, 204 ; bibliography, 487. 

Primings, disposition of, 217. 

Pruning tools, 225. 

Pruning wounds, 226. 

Pseudococcus citri, 421. 

Puddling roots, 155. 

Puffing, 329. 

Punctures, caused by stems, 278 ; 
box-nails, 279 ; thorns, 279. 

Purple scale, 414. 

Pythiacystis citrophthora, 365 ; 
causing fruit decay, 386. 

Quality, in tropical grown citrus 

fruits, 25. 
Quarantine, horticultural, 6. 
Quincunx planting, 148. 

Radiation, 234 ; checking of, 244 ; 

of electric orchard heaters, 251. 
Rag, importance in judging, 134. 
Railroads, early shipments by rail, 

5. 



516 



Index 



Rainfall, 26 ; as affecting irrigation, 
188. 

Recipes, 341. 

Red blotch of lemon, described, 398. 

Red rot, see red blotch. 

Red scale, discussion of, 411 ; dis- 
tribution of, 404. 

Red spiders, discussion of, 423. 

Reed, J. H., 23. 

Refrigeration, cost of, 360. 

Reheading, mature trees, 220 ; 
young trees, 218. 

Re-icing, cost of, rate case con- 
cerning, 298. 

Relative humidity of air, as affect- 
ing irrigation, 188. 

Relative size in fumigation dosage, 
451. 

Respiration, of oranges, 277. 

Reversion, 120. 

Rhizoctonia, 391. 

Right of diversion, 298. 

Rind, importance in judging, 133 ; 
variation in thickness of, 328. 

Ringing, 48. 

Rings of growth, 47. 

Ripening season, Northern Valley, 
31. 

Risso, 40. 

Rivers, Thomas, 70, 15. 

River's Navel orange, 16. 

Riverside, first settled, 3 ; citrus 
fairs, 19, 5. 

Riverside Press and Horticulturist, 
quoted, 19. 

Roosevelt, President, 22. 

Root-rot, due to sclerotinia, 383 ; 
due to toadstools, 373. 

Roots, distribution in soil, effect 
of shearing, 45 ; effect of hardpan 
on, 143 ; injured by exposure to 
air, 91 ; cut by plow, 156 ; of 
lemon, susceptible to foot-rot, 
372 ; affected by nematodes, 454. 

Root-stock, 151 ; trifoliata suitable 
for kumquats, 83 ; trifoliata best 



for Unshiu, 79 ; cold resisting, 
155 ; proportion of different kinds 
planted, 84 ; Chinese lemon, 6. 

Root systems, references to litera- 
ture, 481. 

Rose beetle, 429. 

Rutacere, 42. 

Saissetia hemisphserica, 420. 

Saissetia olese, 405. 

Sales, classification of, 344 ; divi- 
sion of Exchange, 350. 

Salesmen, of Exchange, 348. 

Salt River Valley, 23. 

San Gabriel Mission, site of first 
orchard, 2. 

Santa Fe Railway, 5. 

Sap Currents, nature of, 47 ; rela- 
tion to tree parts, 47. 

Satsuma orange, production of 
seeds in, 56 ; susceptibility to 
frost, 242. 

Saunders, William, 17. 

Savastano, 121. 

Saws, for pruning, 225. 

Scab, description of, 395. 

Scale insects, effect of climate on, 
404 ; exclusion of, 357 ; ridding 
seed-bed stock of, 90; red, 411; 
yellow, 414; black, 405 ; purple, 
414 ; brown, 418 ; gray, 410 ; 
cottony cushion, 417; greedy, 
420 ; citricola, 419 ; hemispheri- 
cal, 420 ; oleander, 420. 

Scales, for judging, 132. 

Scaly-bark, 367 ; Florida type, 395. 

Scars, on fruit, 321. 

Schedules, fumigation dosage, 444- 
447. 

Schizophyllum commune, 399. 

Scientific American, 48. 

Scions, references to literature, 478. 

Sclerotinia libertiniana, causing 
fruit decay, 382. 

Score-card, for citrus land, 139 ; 
for bearing groves, 363 ; for 



Index 



517 



oranges, 133 ; for lemons, 134 ; 
for pomelos, 136 ; for packed 
boxes, 137 ; for feature exhibits, 
138. 

Scratches, caused by shoes of 
pickers, 280 ; caused by finger- 
nails, 279 ; gravel, 279 ; thorns, 
279. 

Scutellista cyanea, 409. 

Season, of picking, 63. 

Seed-bed, planting, 84. 

Seed-bed stock, price, method of 
pulling, 88 ; trimming back when 
transplanting, 92. 

Seed, citrus, description of different 
kinds, 84 ; cost, 84 ; method of 
keeping, 86 ; number per bushel, 
86. 

Seedlessness, importance of in 
pomelos, 77. 

Seedling trees, compared with 
budded trees, 65 ; 84. 

Seeds, presence of, in judging, 134, 
136 ; time of planting, 88 ; effect 
of freezing on germination, 86 ; 
first planted in California, 1. 

Seeds of citrus fruits, number of, 
61. 

Selected buds, importance of, 357. 

Selection of bud-wood, effect of 
poor bud-wood, 114. 

Selling, average cost of, 360. 

Separators, for frosted fruit, 272. 

Setting of fruit, as affected by plow- 
ing, 166. 

Seville orange, susceptibility to 
frost, 242. 

Shaddock, description of, 81. 

Shading, of nursery plants, 38. 

Shamel, A. D., 124. 

Shears, for pruning, 225. 

Shields, for tillage implements, 170. 

Shipments, annual, in carloads, 9. 

Shipping, lemons, 312 ; first car 
shipped east, 3 ; nursery stock, 
103. 



Shorb, J. de Barth, 18. 

Shoulder spots, 323. 

Silver mite, discussion of, 424. 

Silverware, as premiums, 351. 

Site, for planting, 139. 

Six-spotted mite, 423. 

Size, importance in judging, 135. 

Sizing, lemons, 310; machines, 
292. 

Slitting bark, of young trees, 206. 

Slope, of land for irrigation, 201 ; 
best for planting, 150. 

Smith, C. O., cited, 401. 

Smith, R. E., quoted, 378. 

Smoke, from orchard heaters, 253. 

Smudge fuel, 250. 

Snowden, R. R., cited, 377. 

Sodium cyanide, for fumigation, 
449. 

Sodium sulfate, a waste product of 
fumigation, 439. 

Soft brown scale, discussion of, 418. 

Soil, nitrification and ammonifica- 
tion, 379 ; heavy soil may en- 
courage gum-disease, 365 ; most 
desirable, 357 ; samples, 196 
inoculation, 183; tillage of, 165 
alkali, 144 ; ideal for citrus, 144 
for seed-bed, 87. 

Soil acidity, 144. 

Soil adaptations, 142. 

Soil analysis, 144. 

Soils, relation to mottled-leaf, 378 ; 
kinds as affecting method of irri- 
gation, 200 ; kinds not benefited 
by cover-crop, 183 ; humus con- 
tent, 179 ; analyses of, 175 ; cul- 
tivation and management, 170 ; 
for seed-bed stock, 91 ; northern 
coast division, 32 ; Interior 
Valley division, 31 ; Southern 
Coast division, 29 ; references to 
literature, 481. 

Soil scars, on fruit, 323. 

Soil types, 142. 

Solanum nigrum, 404. 



518 



Index 



Sonora, citrus production in, 23. 

Sour clover, as cover-crop, 182. 

Sour-stock, as a root, 152. 

South Africa, 14 ; frost in, 25. 

Southern Pacific Railway, 5. 

Spain, frost in, 25. 

Special equipment, for packing- 
houses, 299. 

Speculation, encouraged by over- 
capitalization, 356. 

Speculators, 344. 

Sphseropsis tumefaciens, 401. 

Sphagnum, for packing bud-wood, 
94 ; for packing seed-bed stock, 
90. 

Splits, as blemishes, 326. 

Splitting of bark, effect of frost on, 
219. 

Spores, of fungi in wash water, 385. 

Spotting, of Navel oranges in tran- 
sit, 389. 

Spraying, cost of, 361. 

Spraying under trees, as prevention 
for brown-rot, 387. 

Square planting, 148. 

Squirrels, as pests, 458. 

Staking young trees, in orchard, 
218. 

Standard car, number of boxes in, 
295 ; arrangement of boxes in, 
295 ; air spaces in, 296. 

Standard grade, 292. 

Standpipes, for irrigation, 194. 

State Commission of Horticulture, 
influence on industry, 11 ; descrip- 
tion of, 106. 

State Fruit Growers' Convention, 
109. 

Statute inch, 192. 

Stem, importance in judging, 133. 

Stem end rot, 394. 

Stem end spot, in California, 399 ; 
of oranges, 320. 

Stem punctures, 321, 278. 

Stenciling, of boxes, 293 ; impor- 
tance in judging, 137. 



Stevens, H. E., cited, 392. 

Stock, see Root-stock, 152. 

Stocks, references to literature, 478. 

Storage, 306. 

Storing, references to literature, 
489. 

Strap, proper position of, 138. 

Straw, plowed under, a cause of 
mottled-leaf, 379. 

Structure of the fruit, morphologi- 
cal, 60. 

Strychnine, as poison for gophers, 
457. 

Subsoiling, 166. 

Subsoils, 143. 

Sucker growths, 208. 

Sucker-nests, 226. 

Suckers, effect of presence of, 209 ; 
not desirable for bud-wood, 95. 

Sucking insects, 405. 

Sugar, reduction of, during respira- 
tion, 287. 

Sugars, in citrus fruit, 63. 

Sulfur, remedy for red spider, 424. 

Sulfuric acid, for fumigation, 439. 

Sunburn, of bark, encourages schizo- 
phyllum, 400. 

Sunburn, of leaves, 368 ; of fruit, 
324. 

Sunburning, bark of pruned trees, 
219. 

"Sunkist" label, 292, 351. 

Sunlight, effect of over-illumina- 
tion, 38 ; as affecting irrigation, 
188. 

Sun protectors, 157. 

Supply cart, for fumigators, 438. 

Supply Department, of Exchange, 
350. 

Sweating, lemons, 305 ; oranges, 
282 ; of Valencia oranges, 282 ; 
references to literature, 489. 

Sweat room, description of, 289, 
305 ; construction of, 289 ; tem- 
perature of, 290 ; heating of, 290 ; 
arrangement of fruit in, 290. 



Index 



519 



Sweet orange, antiquity, introduc- 
tion into Europe, introduction 
into Brazil, 41. 

Swingle, W. T., 79. 

Swingle-Webber hybrids, varieties, 
Rusk, 79; Willits, 79; Norton, 
79; Colman, 79; Savage, 79; 
Rustic, 79 ; Thornton, 80 ; Samp- 
son, 80; Weshart, 80; Trimble, 
80. 

Taber, G. L., cited, 155. 
Tait, C. E., quoted, 170. 
Tangelo, 79. 

Tangerines, picking, 312. 
Tanking newly planted trees, 158. 
Tannin, treatment for fumigating 

tents, 435. 
Tar, for pruning wounds, 228. 
Tariff, references to literature, 490 ; 

protective duties, 9. 
Taxes, 357 ; and incidentals, cost 

of, 359. 
Teague, R. M., 77, 69. 
Temperature, effect on fumigation, 
448 ; of air, as affecting irriga- 
tion, 188. 
Tent fumigation, of citrus trees, 

435. 
Tents, for storing lemons, 308 ; 
cost of, 452 ; acid holes in, 438 ; 
equipment of, 437; methods of 
marking, 436 ; fumigation, 435. 
Teratological forms, 326, 120. 
Terraced planting, 150. 
Tetranychus mytilaspidis, 423. 
Tetranychus sexmaculatus, 423. 
Texture, importance in judging, 

136. 
Thawing, of frozen fruit, 249. 
Thermal belts, 236. 
Thinning, of fruit, 323; advis- 
ability of, 282. 
Thomas, E. E., cited, 378, 449. 
Thomson, A. C, 68. 
Thorns, 51. 



Thorn-stabs, 321. 
Thrips, discussion of, 425. 
Tibbet, Luther C, and wife, 17, 18. 
Tillage, 165. 

Tincture of orange flowers, 338. 
Toadstool root-rot, 373. 
Tomocera californica, 410. 
Tools, for pruning, 225. 
Topography, as affecting frosts, 238. 
Top-working, 223, 92. 
Tortrix citrana, description of, 428. 
Tractors, for plowing, 168. 
Traffic, division of Exchange, 350. 
Training young trees, 100. 
Transit, time required for, dis- 
tance covered, 298. 
Transpiration, in fruit, 61. 
Trapping gophers, 456. 
Tree protectors, 157. 
Tree-ripes, 305 ; lemons, suscep- 
tible to black pit, 401. 
Trees, cost of, 359 ; number of, to 

the acre, 149. 
Triangular planting, 147. 
Trifoliata, susceptibility to frost, 

242 ; as a root-stock, 153. 
Trifoliate orange,' rare in California, 

83. 
Tripeta ludens, 24; quarantine 

against, 109. 
Trunk rot, 399. 
Turgidity of rind, dangers from, 

278. 
Twelve-spotted beetle, 430. 
Twig blight, 382. 
Twig-gumming, 367. 
Tylenchulus semipenetrans, 449. 
Types, of fruit, 123. 

Underwood-Simmons tariff, 9. 

University of California, 11. 

U. S. Department of Agriculture, 

citrus hybrids distributed by, 79 ; 

influence on industry, 11. 
U. S. Supreme Court, decision in 

pre-cooling case, 298. 



520 



Index 



Vaile, R. S., 455. 

Valencia orange, how pruned, 212 ; 
sweating of, 282 ; origin of and 
conditions best suited for, 70 ; 
pollination of, 55. 

Varieties, descriptions of, 65 ; bib- 
liography, 485. 

Vegetables, grown between trees, 
159. 

Ventilation, for stored lemons, 308. 

Verrucosis, 395. 

Vesicles, as affected by frost, 274 ; 
arrangement of, 60. 

Vetch, as host for cottony mold, 
383 ; common, as cover-crop, 
182 ; hairy, as cover-crop, 182. 

Vicia sativa, as cover-crop, 182. 

Vinegar, from oranges, 336. 

Wages, of lemon pickers, 317. 

Wagons, 304. 

Wallace, J. C, 16. 

Washington Navel orange, descrip- 
tion of, climatic and soil condi- 
tions best suited to, sporting 
habits, sub-varieties, 66 ; com- 
position of, 62 ; seedlings of, 59 ; 
production of seeds in, occur- 
rence of normal embryo sacs in, 
56-57 ; pollination of, 55 ; his- 
tory of introduction, first ex- 
hibited in California, 19 ; present 
location of two trees first brought 
to California, 23 ; sports of, 128 ; 
how pruned, 207. 

Wash water, disinfection of, 291. 

Water, amount necessary for irri- 
gation, 188 ; application to young 
trees, 158; disposition of waste, 
150, 144 ; loss of, from fruit, 61'; 
average cost of, 361 ; methods 
of application, 198 ; time of 
application, 195 ; temperature 
of, 196 ; methods of distribution, 
193 ; lifting, for irrigation, 193 ; 
underground, laws in regard to, 



192 ; cost of, 193 ; sources of, 
192; measurement, 191. 

Watering seed-beds, 391. 

Water right, 142 ; cost of, 359 

Water supply, importance of, 357 ; 
for irrigation, 141. 

Webber, H. J., 79. 

Weeds, as hosts for scale insects, 404. 

White, A. S., 19. 

White fly, quarantine against, 109. 

Whitewash, for pruning wounds, 
228; prevents sunburn of bark, 
219. 

Wind, as affecting frost, 233, 235; 
as affecting irrigation, 188 ; arti- 
ficial, as frost protection, 248 ; 
causing blemishes of fruit, 320 ; 
effect on fumigation, 448. 

Windbreaks, 37, 38. 

Windfalls, 324. 

Winds, effect on trees, 36. 

Wire baskets, 250. 

Wither-tip, description of, 380. 

Woglum, R. S., 433. 

Wolf & Massey, 393. 

Wolfskill, Louis, 17. 

Wolfskill, William, first commer- 
cial orchard, 2. 

Wood, structure, 46. 

Woodworth, C. W., 446; dosage 
table, 450. 

Workman, C. R., 74. 

Works, J. D., cited, 161. 

Wounds, dressings for, 226 ; heal- 
ing of, 49. 

Wrappers, redeemable for pre- 
miums, 351. 

Wrapping, value in judging, 138. 

Xanthoxylum americanum, 42. 

Yellow scale, discussion of, 414. 
Yellow spotting of oranges, 398. 
Yields, 127, 129, 359; lemon and 

orange compared, 191 ; average 

obtained, 362. 
Yuma, citrus planting at, 23. 



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and Britannica of the garden-folk, amateur and professional alike. 
And the remarkable thing is that, while it is fundamentaly a work 
of reference, it also contains limitless quantities of good reading of 
the sort dear to the heart of the garden enthusiast." — The Nation. 

"It is no exaggeration to state that Bailey's new work is the best 
cyclopedia obtainable for all who are connected, either remotely or 
intimately, as amateurs or professionals, with horticultural pursuits. 
It is the best for the student of botany who is investigating the subject 
in a purely scientific way; best for the commercial grower who likes 
to be well informed on matters in general and his own trade in par- 
ticular, and best for the other sort of commercial grower, who does 
not bother himself particularly about hunting for any information 
except such as will give him immediate help in producing a better 
crop." — The Florist's Review. 



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